Apparatus and method for polishing semiconductor wafers

ABSTRACT

An apparatus and method for polishing semiconductor wafers uses multiple polishing surfaces, multiple polishing heads and multiple wafer stations to sequentially polish the semiconductor wafers. The wafer stations includes at least one wafer load-unload station to transfer the semiconductor wafers between the wafer load-unload station and the polishing heads.

CROSS REFERENCE TO RELATED APPLICATION

This application is entitled to the benefit of U.S. Provisional Patent Application Ser. Nos. 60/836,278, filed on Aug. 8, 2006, 60/837,276, filed on Aug. 10, 2006, 60/840,192, filed on Aug. 25, 2006, 60/840,143, filed on Aug. 26, 2006, and 60/844,150, filed on Sep. 12, 2006, which are all incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to semiconductor processing equipments, and more particularly to an apparatus and method for polishing semiconductor wafers.

BACKGROUND OF THE INVENTION

Local and global planarization of semiconductor wafers becomes increasingly important as more metal layers and interlayer dielectric layers are stacked on the wafers. A preferred method to planarize semiconductor wafers is the chemical mechanical polishing (CMP) method, where a surface of a semiconductor wafer is polished using a slurry solution supplied between the wafer and a polishing pad. The CMP method is also widely used for damascene process to form copper structures on the semiconductor wafers.

In general, a CMP equipment includes a polishing table where a polishing pad is placed and a wafer carrier that supports a semiconductor wafer and presses the wafer against the polishing pad. The CMP equipment may also include a wafer cleaner to clean and dry the polished wafers.

One of the most important considerations of a CMP equipment is productivity. For higher productivity, a CMP equipment typically requires more polishing tables and more wafer carriers. As the number of polishing tables and wafer carriers included in a CMP equipment is increased, the arrangement of the polishing tables and the wafer carriers becomes important to efficiently polish multiple semiconductor wafers. Furthermore, the manner in which the semiconductor wafers are transferred to and from the wafer carriers and the wafer cleaner becomes important as well. However, the footprint of a CMP equipment must also be considered since a CMP equipment with a large footprint requires a larger clean room to house the equipment, which translates into greater cost of operation.

In view of these issues, what is needed is an apparatus and method for polishing semiconductor wafers with high productivity, which does not require a large footprint.

SUMMARY OF THE INVENTION

An apparatus and method for polishing semiconductor wafers uses multiple polishing surfaces, multiple polishing heads and multiple wafer stations to sequentially polish the semiconductor wafers. The wafer stations include at least one wafer load-unload station to transfer the semiconductor wafers between the wafer load-unload station and the polishing heads.

An apparatus for polishing semiconductor wafers in accordance with an embodiment of the invention comprises first, second and third polishing surfaces, first, second and third wafer stations, and a rotation assembly. The first, second and third polishing surfaces are positioned around a rotational axis. The first, second and third wafer stations are positioned around the rotational axis between the first, second and third polishing surfaces such that each of the first, second and third wafer stations is positioned between adjacent polishing surfaces of the first, second and third polishing surfaces. The first wafer station is a wafer load-unload station configured to receive a semiconductor wafer so that the semiconductor wafer is unloaded onto the first wafer station before being transferred from the first wafer station. The rotation assembly includes first, second and third polishing heads. The rotation assembly is configured to rotationally move each of the first, second and third polishing heads about the rotational axis between at least some of the first, second and third polishing surfaces and the first, second and third wafer stations. The number of polishing heads, the number of polishing surfaces and the number of wafer stations included in the apparatus are the same.

An apparatus for polishing semiconductor wafers in accordance with another embodiment of the invention comprises first, second and third polishing surfaces, first, second, third and fourth wafer load-unload stations, and a rotation assembly. The first, second and third polishing surfaces are positioned around a rotational axis. The first, second, third and fourth wafer load-unload stations are positioned around the rotational axis between the first, second and third polishing surfaces such that the second wafer load-unload station is positioned between the first and second polishing surfaces, the third wafer load-unload station is positioned between the second and third polishing surfaces, and the first and fourth wafer load-unload stations are positioned between the first and third polishing surfaces. The rotation assembly includes first, second and third polishing heads. The rotation assembly is configured to rotationally move each of the first, second and third polishing heads about the rotational axis between at least some of the first, second and third polishing surfaces and the first, second, third and fourth wafer load-unload stations.

An apparatus for polishing semiconductor wafers in accordance with another embodiment of the invention comprises first and second polishing surfaces, first and second wafer load-unload stations, and a rotation assembly. The first and second polishing surfaces are positioned around a rotational axis. The first and second load-unload wafer stations are positioned around the rotational axis between the first and second polishing surfaces such that each of the first and second wafer stations is positioned between the first and second polishing surfaces. Each of the first and second wafer load-unload stations is configured to receive a semiconductor wafer so that the semiconductor wafer is unloaded onto the first and second wafer load-unload stations before being transferred from the first and second wafer load-unload stations. The rotation assembly including first and second polishing heads. The rotation assembly is configured to rotationally move each of the first and second polishing heads about the rotational axis between at least some of the first and second polishing surfaces and the first and second wafer load-unload stations. The number of polishing heads, the number of polishing surfaces and the number of wafer load-unload stations included in the apparatus are the same.

An apparatus for polishing semiconductor wafers in accordance with another embodiment of the invention comprises first and second polishing surfaces, first and second wafer stations, and a rotation assembly. The first and second polishing surfaces are positioned around a rotational axis such that centers of the first and second polishing surfaces and the rotational axis define a first straight line. The first and second wafer stations are positioned around the rotational axis between the first and second polishing surfaces such that each of the first and second wafer stations is positioned between the first and second polishing surfaces and centers of the first and second wafer stations and the rotational axis define a second straight line. The first and second wafer stations are arranged with respect to the first and second polishing surfaces such that the first straight line is not perpendicular to the second straight line. The rotation assembly includes first and second polishing heads. The rotation assembly is configured to rotationally move each of the first and second polishing heads about the rotational axis between at least some of the first and second polishing surfaces and the first and second wafer stations. The number of polishing heads, the number of polishing surfaces and the number of wafer stations included in the apparatus are the same.

An apparatus for polishing semiconductor wafers in accordance with another embodiment of the invention comprises first and second polishing surfaces, first, second and third wafer load-unload stations, and a rotation assembly. The first and second polishing surfaces are positioned around a rotational axis. The first, second and third wafer load-unload stations are positioned around the rotational axis between the first and second polishing surfaces such that the first and third load-unload stations are positioned between the first and second polishing surfaces and the second load-unload station is positioned between the first and second polishing surfaces. The rotation assembly includes first and second polishing heads. The rotation assembly is configured to rotationally move each of the first and second polishing heads about the rotational axis between at least some of the first and second polishing surfaces and the first, second and third wafer load-unload stations.

A system for polishing semiconductor wafers in accordance with an embodiment of the invention comprises first and second polishing apparatuses, a wafer transfer device and a post-CMP cleaner. Each of the first and second polishing apparatuses comprises first, second and third polishing surfaces, first, second and third wafer stations, and a rotation assembly. The first, second and third polishing surfaces are positioned around a rotational axis. The first, second and third wafer stations are positioned around the rotational axis between the first, second and third polishing surfaces such that each of the first, second and third wafer stations is positioned between adjacent polishing surfaces of the first, second and third polishing surfaces. The first wafer station is a wafer load-unload station configured to receive a semiconductor wafer so that the semiconductor wafer is unloaded onto the first wafer station before being transferred from the first wafer station. The rotation assembly includes first, second and third polishing heads. The rotation assembly is configured to rotationally move each of the first, second and third polishing heads about the rotational axis between at least some of the first, second and third polishing surfaces and the first, second and third wafer stations. The wafer transfer device is positioned adjacent to the first and second polishing apparatuses to access the first wafer station of each of the first and second polishing apparatuses. The post-CMP cleaner is positioned adjacent to the wafer transfer device such that the wafer transfer device is positioned between the post-CMP cleaner and the first and second polishing apparatuses. The post-CMP cleaner is configured to clean the semiconductor wafers that have been polished in one of the first and second polishing apparatuses and transferred to the post-CMP cleaner by the wafer transfer device.

A system for polishing semiconductor wafers in accordance with another embodiment of the invention comprises first and second polishing apparatuses and a wafer transfer device. Each of the first and second polishing apparatuses comprises first, second and third polishing surfaces, first, second and third wafer stations, and a rotation assembly. The first, second and third polishing surfaces are positioned around a rotational axis. The first, second and third wafer stations are positioned around the rotational axis between the first, second and third polishing surfaces such that each of the first, second and third wafer stations is positioned between adjacent polishing surfaces of the first, second and third polishing surfaces. The first wafer station is a wafer load-unload station configured to receive a semiconductor wafer so that the semiconductor wafer is unloaded onto the first wafer station before being transferred from the first wafer station. The rotation assembly including first, second and third polishing heads. The rotation assembly is configured to rotationally move each of the first, second and third polishing heads about the rotational axis between at least some of the first, second and third polishing surfaces and the first, second and third wafer stations. The wafer transfer device is positioned adjacent to the first and second polishing apparatuses to access the first wafer station of each of the first and second polishing apparatuses. The first and second polishing apparatuses are orientated such that the first wafer station and the first and third polishing surfaces of each of the first and second polishing apparatuses are closer to the wafer transfer device than the second and third wafer stations and the second polishing surface.

A method for polishing semiconductor wafers in accordance with an embodiment of the invention comprises transferring a semiconductor wafer between a first wafer station of a polishing apparatus and one of first, second and third polishing heads of a rotation assembly of the polishing apparatus, the first wafer station being a wafer load-unload station, sequentially polishing the semiconductor wafer on first, second and third polishing surfaces of the polishing apparatus using at least one of the first, second and third polishing heads of the rotation assembly, and sequentially transferring the semiconductor wafer to second and third wafer stations of the polishing apparatus using at least one of the first, second and third polishing heads of the rotation assembly, each of the first, second and third wafer stations being positioned between adjacent polishing surfaces of the first, second and third polishing surfaces.

A method for polishing semiconductor wafers in accordance with another embodiment of the invention comprises transferring a semiconductor wafer between a first wafer load-unload station of a polishing apparatus and one of first and second polishing heads of a rotation assembly of the polishing apparatus, sequentially polishing the semiconductor wafer on first and second polishing surfaces of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly, and transferring the semiconductor wafer to a second wafer load-unload station of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly after the semiconductor wafer is polished on the first polishing surface, including unloading the semiconductor wafer onto the second wafer load-unload station, each of the first and second wafer load-unload stations being positioned between the first and second polishing surfaces.

A method for polishing semiconductor wafers in accordance with another embodiment of the invention comprises transferring a semiconductor wafer between a first wafer station of a polishing apparatus and one of first and second polishing heads of a rotation assembly of the polishing apparatus, the first wafer station being a wafer load-unload station, sequentially polishing the semiconductor wafer on first and second polishing surfaces of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly, the first and second polishing surfaces being positioned around a rotational axis such that centers of the first and second polishing surfaces and the rotational axis define a first straight line, and transferring the semiconductor wafer to a second wafer station of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly after the semiconductor wafer is polished on the first polishing surface, the first and second wafer stations being positioned around the rotational axis between the first and second polishing surfaces such that each of the first and second wafer stations is positioned between the first and second polishing surfaces and centers of the first and second wafer stations and the rotational axis define a second straight line, the first and second wafer stations being arranged with respect to the first and second polishing surfaces such that the first straight line is not perpendicular to the second straight line.

A method for polishing semiconductor wafers in accordance with another embodiment of the invention comprises transferring a semiconductor wafer to a first wafer station of a polishing apparatus using a wafer transfer device, the first wafer station being a wafer load-unload station, sequentially transferring the semiconductor wafer to first, second and third polishing surfaces of the polishing apparatus using first, second and third polishing heads, respectively, of a rotation assembly of the polishing apparatus, sequentially polishing the semiconductor wafer on the first, second and third polishing surfaces of the polishing apparatus using the first, second and third polishing heads, respectively, of the rotation assembly, sequentially transferring the semiconductor wafer to second, third and fourth wafer stations of the polishing apparatus using the first, second and third polishing heads, respectively, of the rotation assembly, the first wafer station being positioned between the fourth wafer station and the first polishing surface, the second wafer station being positioned between the first and second polishing surfaces, the third wafer station being positioned between the second and third polishing surfaces, and the fourth wafer station being positioned between the third polishing surface and the first wafer station, and removing the semiconductor wafer from the fourth wafer station of the polishing apparatus using the wafer transfer device, the fourth wafer station being another wafer load-unload station.

A method for polishing semiconductor wafers in accordance with another embodiment of the invention comprises transferring a semiconductor wafer to a first wafer station of a polishing apparatus using a wafer transfer device, the first wafer station being a wafer load-unload station, sequentially transferring the semiconductor wafer to first and second polishing surfaces of the polishing apparatus using first and second polishing heads, respectively, of a rotation assembly of the polishing apparatus, sequentially polishing the semiconductor wafer on the first and second polishing surfaces of the polishing apparatus using the first and second polishing heads, respectively, of the rotation assembly, sequentially transferring the semiconductor wafer to second and third wafer stations of the polishing apparatus using the first and second polishing heads, respectively, of the rotation assembly, the first wafer station being positioned between the third wafer station and the first polishing surface, the second wafer station being positioned between the first and second polishing surfaces, the third wafer station being positioned between the second polishing surface and the first wafer station, and removing the semiconductor wafer from the third wafer station of the polishing apparatus using the wafer transfer device, the third wafer station being another wafer load-unload station.

Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a polishing apparatus when polishing heads are positioned over wafer load-unload stations in accordance with an embodiment of the invention.

FIG. 2 is a top view of the polishing apparatus of FIG. 1 when the polishing heads are positioned over polishing surfaces in accordance with an embodiment of the invention.

FIG. 3 is another top view of the polishing apparatus of FIG. 1 when the polishing heads are positioned over different wafer load-unload stations in accordance with an embodiment of the invention.

FIG. 4 is a top view of a wafer load-unload station, which can be used in the polishing apparatus of FIG. 1, in accordance with an embodiment of the invention.

FIG. 5 is a cross-sectional view of the load-unload station of FIG. 4.

FIGS. 6( a) and 6(b) are sequential cross-sectional views of the load-unload station of FIG. 4 to show a sequence of loading a wafer W onto a polishing head in accordance with an embodiment of the invention.

FIG. 7 is a top view of a polishing system that includes the polishing apparatus of FIG. 1 in accordance with an embodiment of the invention.

FIG. 8 is a top view of a polishing apparatus with rotatable washing arms when polishing heads are positioned over wafer load-unload stations in accordance with another embodiment of the invention.

FIG. 9 is a partial side view of the polishing apparatus of FIG. 8.

FIG. 10 is another top view of the polishing apparatus of FIG. 8 when the polishing heads are positioned over polishing surfaces.

FIG. 11 is a top view of a polishing apparatus when polishing heads are positioned over wafer load-unload stations in accordance with another embodiment of the invention.

FIG. 12 is a top view of a polishing apparatus with a pivoting wafer transfer device when a wafer load-unload cup of the device is positioned at a parking position X in accordance with another embodiment of the invention.

FIG. 13 is another top view of the polishing apparatus of FIG. 12 when the wafer load-unload cup of the pivoting wafer transfer device is positioned at a wafer transfer position Y.

FIG. 14 is a partial side view of the polishing apparatus of FIG. 12.

FIG. 15 is a top view of a polishing apparatus with pivoting mechanisms for pivoting polishing heads in accordance with another embodiment of the invention.

FIG. 16 is another top view of the polishing apparatus of FIG. 15.

FIG. 17 is a partial side view of the polishing apparatus of FIG. 15.

FIG. 18 is a top view of a polishing apparatus with two polishing surfaces, two polishing heads and two wafer load-unload stations in accordance with another embodiment of the invention.

FIG. 19 is a top view of the polishing apparatus of FIG. 18 with the wafer load-unload stations being positioned in a different arrangement in accordance with another embodiment of the invention.

FIG. 20 is a top view of a polishing apparatus with two polishing surfaces, two polishing heads and three wafer load-unload stations in accordance with another embodiment of the invention.

FIG. 21 is a top view of a polishing apparatus with three polishing surfaces, three polishing heads and four wafer load-unload stations in accordance with another embodiment of the invention.

FIG. 22 is a flow diagram of a method for polishing semiconductor wafers in accordance with an embodiment of the invention.

FIG. 23 is a flow diagram of a method for polishing semiconductor wafers in accordance with another embodiment of the invention.

FIG. 24 is a flow diagram of a method for polishing semiconductor wafers in accordance with another embodiment of the invention.

FIG. 25 is a flow diagram of a method for polishing semiconductor wafers in accordance with another embodiment of the invention.

FIG. 26 is a flow diagram of a method for polishing semiconductor wafers in accordance with another embodiment of the invention.

DETAILED DESCRIPTION

With reference to FIGS. 1-3, a polishing apparatus 1A according to an embodiment of the invention is described. The polishing apparatus 1A comprises three polishing surfaces 10 a-10 c, three polishing heads 20 a-20 c and three wafer load-unload stations 15 a-15 c. The polishing apparatus 1A can further comprise a wafer transfer device 50. The polishing apparatus 1A is capable of sequentially processing multiple semiconductor wafers, as described in more detail below.

FIG. 1 shows the polishing apparatus 1A when the first, second and third polishing heads 20 a-20 c are positioned over the first, second and third wafer load-unload stations 15 a-15 c, respectively. FIG. 2 shows the polishing apparatus 1A when the first, second and third polishing heads 20 a-20 c are positioned over the first, second and third polishing surfaces 10 a-10 c, respectively. FIG. 3 shows the polishing apparatus 1A when the first, second and third polishing heads 20 a-20 c are positioned over the second, third and first wafer load-unload stations 15 b, 15 c and 15 a, respectively. As used herein, “positioned over” means being vertically aligned such that one object, e.g., one of the polishing head 20 a-20 c, is directly above another object, e.g., one of the wafer load-unload stations 15 a-15 c.

The polishing heads 20 a-20 c are attached to a rotation assembly 12, which operates to rotate the polishing heads between the polishing surfaces 10 a-10 c and the wafer load-unload stations 15 a-15 c. The rotation assembly 12 includes rotational-and-vertical drive mechanisms 25 a-25 c, supporting arms 45 a-45 c, a rotational shaft 30 and a central rotational-and-vertical drive mechanism 35. The polishing heads 20 a-20 c are coupled to their respective rotational-and-vertical drive mechanisms 25 a-25 c, which control rotational and vertical motions of the respective polishing heads 20 a-20 c. The respective rotational-and-vertical drive mechanisms 25 a-25 c are connected to their respective supporting arms 45 a-45 c, which are attached to the rotational shaft 30.

The supporting arms 45 a-45 c are configured or designed such that the distance between the rotational axis 36 of the rotational shaft 30 and the center of the first polishing head 20 a, the distance of the rotational axis 36 of the rotational shaft 30 and the center of the second polishing head 20 b and the distance of the rotational axis 36 of the rotational shaft 30 and the center of the third polishing head 20 c are substantially equal.

The rotational shaft 30 is connected to the central rotational-and-vertical drive mechanism 35, which controls rotational and vertical motions of the rotational shaft 30. Thus, the supporting arms 45 a-45 c and the polishing heads 20 a-20 c are rotated in unison about the rotational axis 36 of the rotational shaft 30 by the central rotational-and-vertical drive mechanism 35.

In this embodiment, the supporting arms 45 a-45 c, the wafer load-unload stations 15 a-15 c and the polishing surfaces 10 a-10 c are arranged such that (1) the first polishing head 20 a can be moved exclusively between the first wafer load-unload station 15 a, the first polishing surface 20 a and the second wafer load-unload station 15 b; (2) the second polishing head 20 b can be moved exclusively between the second wafer load-unload station 15 b, the second polishing surface 20 b and the third wafer load-unload station 15 c; and (3) the third polishing head 20 c can be moved exclusively between the third wafer load-unload station 15 c, the third polishing surface 20 c and the first wafer load-unload station 15 a.

The polishing heads 20 a-20 c are configured to be able to hold semiconductor wafers. Each of the polishing heads 20 a-20 c is designed to hold a single semiconductor wafer. In an embodiment, the polishing heads 20 a-20 c are configured to be able to hold semiconductor wafers using vacuum, which is applied to the bottom surfaces of the polishing heads where the wafers contact the polishing heads. The polishing heads 20 a-20 c are attached to the rotation assembly 12 via the supporting arms 45 a-45 c such that all of the polishing heads are positioned over the polishing surfaces 10 a-10 c when one of the polishing heads is positioned over one of the polishing surfaces and all of the polishing heads are positioned over the wafer load-unload stations 15 a-15 c when one of the polishing heads is positioned over one of the wafer load-unload stations.

The polishing surfaces 10 a-10 c and the wafer load-unload stations 15 a-15 c are further arranged such that (1) the first wafer load-unload station 15 a is positioned between the third and first polishing surfaces 10 c and 10 a; (2) the second wafer load-unload station 15 b is positioned between the first and second polishing surfaces 10 a and 10 b; and (3) the third wafer load-unload station 15 c is positioned between the second and third polishing surfaces 10 b and 10 c. The polishing surfaces 10 a-10 c can be upper surfaces of polishing pads attached to respective rotatable polishing tables. Alternatively, the polishing surfaces 10 a-10 c can be upper surfaces of the rotatable polishing tables. In an embodiment, as illustrated in FIGS. 1-3, the polishing surfaces 10 a-10 c are arranged such that the polishing surfaces are equally spaced to each other around the rotational axis 36.

The wafer load-unload stations 15 a-15 c are further arranged such that the distance between the rotational axis 36 of the rotational shaft 30 and the center of the first wafer load-unload station 15 a, the distance between the rotational axis 36 of the rotational shaft 30 and the center of the second wafer load-unload station 15 b and the distance between the rotational axis 36 of the rotational shaft 30 and the center of the third wafer load-unload station 15 c are substantially equal. In an embodiment, as illustrated in FIGS. 1-3, the wafer load-unload stations 15 a-15 c are arranged such that the wafer load-unload stations are equally spaced to each other around the rotational axis 36.

With reference to FIGS. 4 and 5, a wafer load-unload station 15′ in accordance with an embodiment of the invention is shown. The wafer load-unload station 15′ is an example of a wafer load-unload station that can be used for the wafer load-unload stations 15 a-15 c of the polishing apparatus 1A. FIG. 4 is a top view of the load-unload station 15′ and FIG. 5 is a cross-sectional view of the wafer load-unload station 15′ of FIG. 4 along the line QQ. The wafer load-unload station 15′ comprises a cup base 190, a cup ring 195, a lifter 200, a wafer tray 210, first multiple nozzles 240, second multiple nozzles 250, a drain channel 260, a first fluid channel 270 and a second fluid channel 272. The fluid channels 270 and 272 may be connected to fluid sources (not shown). The drain channel 260 may be connected to a drain pump (not shown).

The cup ring 195 and the wafer tray 210 are mounted on the cup base 190. The wafer tray 210 comprises a hole at the center such that the lifter 200 can be positioned at the center of the cup base 190. The lifter 200 is connected to a lifter pneumatic cylinder 204 through a lift piston 202, as illustrated in FIG. 5. The lifter 200 is a wafer handling device to raise and lower a wafer to and from a polishing head (also known as a wafer carrier), such as one of the polishing heads 20 a-20 c. The lifter 200 is preferably made of soft materials such as rubber to avoid damaging wafer surfaces. The lifter 200 has a surface area that is smaller than the surface area of the wafer being handled by the lifter. The lifter cylinder 204 is connected to the first fluid channel 270 and operated by a fluid supplied through the first fluid channel 270. Nitrogen gas is one example of the fluid that can be used for the lifter cylinder 204. The lifter 200 is moved up and down by the lifter cylinder 204. The lifter 200 is lifted above the top surface of the cup ring 195 to receive a wafer W from a wafer transfer device, such as the wafer transfer device 50, or from a polishing head, such as one of the polishing heads 20 a-20 c. After the lifter 200 receives the wafer W, the lifter is moved down below the wafer tray 210 in order to place the wafer W on the wafer tray 210. In this fashion, the wafer W is unloaded onto the wafer load-unload station 15′.

The first multiple nozzles 240 are mounted on the top of the cup base 190 and the second multiple nozzles 250 are mounted on the interior side of the cup ring 195, as illustrated in FIG. 5. The first and second nozzles 240 and 250 are connected to the second fluid channel 272 and used to spray fluid, such as deionized (DI) water, which is supplied through the second fluid channel 272. Used fluid, e.g., used DI water, is drained through the drain channel 260 by the drain pump (not shown). The first and second multiple nozzles 240 and 250 allow the wafer load-unload station 15′ to wash a wafer and/or a polishing head, when one or both are positioned at the wafer load-unload station 15′.

With reference to FIGS. 6( a) and 6(b), a process sequence for loading a wafer W from the wafer load-unload station 15′ onto a polishing head 20′, which can be one of the polishing heads 20 a-20 c, in accordance with an embodiment of the invention is described. FIGS. 6( a) and (b) are sequential cross-sectional views of the wafer load-unload station 15′ of FIG. 4. After the wafer W is positioned on the wafer tray 210 as previously described with reference to FIG. 5, the polishing head 20′ is placed on the wafer load-unload station 15′, as illustrated in FIG. 6( a). As shown in FIG. 6( a), the polishing head 20′ may include a retainer ring 280 to confine the wafer W during a polishing process. Next, the lifter 200 is moved up and the wafer W on the lifter is received by the polishing head 20′ using a vacuum supplied through vacuum channels 285, as illustrated in FIG. 6( b). After the wafer W is received by the polishing head 20′, the lifter 200 is moved down. For unloading the wafer W from the polishing head 20′, the vacuum provided through the vacuum channels 285 is removed, which releases the wafer W from the polishing head 20′ onto the lifter 200 of the wafer load-unload station 15′. The wafer load-unload station 15′ can then wash the polishing head 20′ by spraying DI water onto the polishing head 20′.

Even though the polishing apparatus 1A has been described as having three polishing surfaces 10 a-10 c, three polishing heads 20 a-20 c and three wafer load-unload stations 15 a-15 c, the polishing apparatus 1A according to other embodiments of the invention can have different numbers of polishing heads, polishing surfaces and wafer load-unload stations. In general, the polishing apparatus 1A comprises N polishing heads, N polishing surfaces and N wafer load-unload stations, where N is an integer larger than one.

With reference to FIGS. 1-3, a method of processing semiconductor wafers in the polishing apparatus 1A in accordance with an embodiment of the invention is described. A first wafer W1 to be processed is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The first wafer W1 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. The unloading and loading of wafers to and from the wafer load-unload stations 15 a-15 c may be similar to the unloading and loading processes described above with respect to the wafer load-unload station 15′. After being loaded onto the first polishing head 20 a, the first wafer W1 is then transferred from the first wafer load-unload station 15 a to the first polishing surface 10 a by rotationally moving the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a. As used herein, a rotational movement of the polishing heads 20 a-20 c is achieved by rotating the rotational shaft 30 about the rotational axis 36. After this rotational movement, the polishing heads 20 a-20 c are positioned over the polishing surfaces 10 a-10 c, respectively, as illustrated in FIG. 2. After the first wafer W1 is removed from the first wafer load-unload station 15 a, a second wafer W2 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a.

After the polishing process is completed, the first wafer W1 is transferred from the first polishing surface 10 a to the second wafer load-unload station 15 b by rotationally moving the first polishing head 20 a from the first polishing surface 10 a to the second wafer load-unload station 15 b. After this movement, the polishing heads 20 a-20 c are positioned over the wafer load-unload stations 15 b, 15 c and 15 a, respectively, as illustrated in FIG. 3.

The first wafer W1 is then unloaded from the first polishing head 20 a to the second wafer load-unload station 15 b in a manner described above with respect to the wafer load-unload station 15′. After the first wafer W1 is unloaded, the first polishing head 20 a is rotationally moved back to the first wafer load-unload station 15 a. After this movement, the polishing heads 20 a-20 c are positioned over the wafer load-unload stations 15 a-15 c, respectively, as illustrated in FIG. 1.

The second wafer W2 is then loaded onto the first polishing head 20 a from the wafer load-unload station 15 a. The first wafer W1 is also loaded onto the second polishing head 20 b from the wafer load-unload station 15 b. The second wafer W2 and the first wafer W1 are then transferred to the first and second polishing surfaces 10 a and 10 b, respectively, by rotationally moving the first and second polishing heads 20 a and 20 b to the first and second polishing surfaces 10 a and 10 b, respectively. After this movement, the polishing heads 20 a-20 c are positioned over the polishing surfaces 10 a-10 c, as illustrated in FIG. 2. After the second wafer W2 is removed from the first wafer load-unload station 15 a, a third wafer W3 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50.

The second wafer W2 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the second wafer W2 on the first polishing surface 10 a involves rotating and pressing the second wafer W2 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying the first slurry to the first polishing surface 10 a.

The first wafer W1 is also polished on the second polishing surface 10 b by the second polishing head 20 b. This polishing process of the first wafer W1 on the second polishing surface 10 b involves rotating and pressing the first wafer W1 on the second polishing surface 10 b by the second polishing head 20 b, rotating the second polishing surface 10 b and supplying a second slurry to the second polishing surface 10 b.

After the polishing processes are completed, the second wafer W2 and the first wafer W1 are transferred to the second and third wafer load-unload stations 15 b and 15 c, respectively, by rotationally moving the first and second polishing heads 20 a and 20 b to the second and third wafer load-unload stations 15 b and 15 c, respectively. After this movement, the polishing heads 20 a-20 c are positioned over the wafer load-unload stations 15 a-15 c, respectively, as illustrated in FIG. 3.

The second wafer W2 is then unloaded from the first polishing head 20 a to the second wafer load-unload station 15 b. The first wafer W1 is also unloaded from the second polishing head 20 b to the third wafer load-unload station 15 c. After the first and second wafers W1 and W2 are unloaded, the first and second polishing heads 20 a and 20 b are rotationally moved back to the first and second wafer load-unload stations 15 a and 15 b, respectively. After this movement, the polishing heads 20 a-20 c are positioned over the wafer load-unload stations 15 a-15 c, respectively, as illustrated in FIG. 1.

The third wafer W3 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. The second wafer W2 is also loaded onto the second polishing head 20 b from the second wafer load-unload station 15 b. The first wafer W1 is also loaded onto the third polishing head 20 c from the third wafer load-unload station 15 c. The third wafer W3, the second wafer W2 and the first wafer W1 are then transferred to the first, second and third polishing surfaces 10 a-10 c, respectively, by rotationally moving the first, second and third polishing heads 20 a-20 c to the first, second and third polishing surfaces 10 a-10 c, respectively. After this movement, the polishing heads 20 a-20 c are positioned over the polishing surfaces 10 a-10 c, respectively, as illustrated in FIG. 2.

The third wafer W3 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the third wafer W3 on the first polishing surface 10 a involves rotating and pressing the third wafer W3 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying the first slurry to the first polishing surface 10 a.

The second wafer W2 is also polished on the second polishing surface 10 b by the second polishing head 20 b. This polishing process of the second wafer W2 on the second polishing surface 10 b involves rotating and pressing the second wafer W2 on the second polishing surface 10 b by the second polishing head 20 b, rotating the second polishing surface 10 b and supplying the second slurry to the second polishing surface 10 b.

The first wafer W1 is also polished on the third polishing surface 10 c by the third polishing head 20 c. This polishing process of the first wafer W1 on the third polishing surface 10 c involves rotating and pressing the first wafer W1 on the third polishing surface 10 c by the third polishing head 20 c, rotating the third polishing surface 10 c and supplying a third slurry to the third polishing surface 10 c.

After the polishing processes are completed, the third wafer W3, the second wafer W2 and the first wafer W1 are transferred to the second, third and first wafer load-unload stations 15 b, 15 c and 15 a, respectively, by rotationally moving the first, second and third polishing heads 20 a-20 c to the second, third and first wafer load-unload stations 15 b, 15 c and 15 a, respectively. After this movement, the polishing heads 20 a-20 c are positioned over the wafer load-unload stations 15 a-15 c, respectively, as illustrated in FIG. 3.

The third wafer W3 is then unloaded from the first polishing head 20 a to the second wafer load-unload station 15 b. The second wafer W2 is also unloaded from the second polishing head 20 b to the third wafer load-unload station 15 c. The first wafer W1 is also unloaded from the third polishing head 20 c to the first wafer load-unload station 15 a.

The first, second and third polishing heads 20 a-20 c are then rotationally moved away from the second, third and first wafer load-unload stations 15 b, 15 c and 15 a, respectively, towards the first, second and third wafer load-unload stations 15 a-15 c, respectively. As the first, second and third polishing heads 20 a-20 c are being rotationally moved, the first wafer W1 is removed from the first wafer load-unload station 15 a by the wafer transfer device 50 and a fourth wafer W4 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50.

The fourth wafer W4 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. The third wafer W3 is also loaded onto the second polishing head 20 b from the second wafer load-unload station 15 b. The second wafer W2 is also loaded onto the third polishing head 20 c from the third wafer load-unload station 15 c. The fourth wafer W4, the third wafer W3 and the second wafer W2 are then transferred to the first, second and third polishing surfaces 10 a-10 c, respectively. The second, third and fourth wafers W2, W3 and W4 are processed further in the polishing apparatus 1A in the same sequential manner as the first wafer W1.

In this sequential manner, multiple wafers can be continuously transferred between the wafer load-unload stations 15 a-15 c and the polishing surfaces 10 a-10 c of the polishing apparatus 1A, and polished on the polishing surfaces 10 a-10 c by the polishing heads 20 a-20 c.

In some embodiments, the polishing surfaces 10 a-10 c can be conditioned by their respective pad conditioners (not shown). In some embodiments, the wafer load-unload stations 15 a-15 c can have multiple DI water spray nozzles, such as the wafer load-unload station 15′, such that the wafers and the polishing heads 20 a-20 c can be washed while the wafers and the polishing heads are positioned at the wafer load-unload stations 15 a-15 c. However, in other embodiments, the wafer load-unload stations 15 a-15 c may not have any DI water spray nozzles, and thus, are not configured to wash the polishing heads 20 a-20 and their wafers. In some embodiments, the wafer load-unload stations 15 a-15 c can have wafer loading and receiving mechanisms, similar to those of the wafer load-unload station 15′, to assist in loading and unloading wafers to and from the polishing heads 20 a-20 c when the polishing heads are positioned over the wafer load-unload stations 15 a-15 c.

Turning now to FIG. 7, a polishing system 100 according to an embodiment of the invention is shown. The polishing apparatus 100 includes two polishing apparatuses 1A-1 and 1A-2, which are identical to the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIG. 7. The polishing system 100 further includes a post-CMP cleaner 150, the wafer transfer device 50, a buffer station 120, a wafer cassette unit 105 and a wafer transfer device 110. The wafer transfer device 50 is mounted on a linear track 55 on which the wafer transfer device 50 can move linearly to access the polishing apparatuses 1A-1 and 1A-2, and the post-CMP cleaner 150. Similarly, the wafer transfer device 110 is mounted on a linear track 115 on which the wafer transfer device 110 can move linearly to access the wafer cassette unit 105, the buffer station 120 and the post-CMP cleaner 150.

As illustrated in FIG. 7, the polishing apparatuses 1A-1 and 1A-2, the post-CMP cleaner 150, the wafer transfer device 50, the buffer station 120, the wafer transfer device 110 are positioned in a service area, while the wafer cassette unit 105 is positioned in a work area. The service area and the work area are defined by a wall 125, which separates these two areas. The wafer transfer device 110 is positioned near the wafer cassette unit 105, but separated from the wafer cassette unit 105 by the wall 125. The post-CMP cleaner is positioned adjacent to the wafer transfer device 110 such that the wafer transfer device 110 is situated between the post-CMP cleaner 150 and the wafer cassette unit 105. The wafer transfer device 50 and the buffer station 120 are positioned between the post-CMP cleaner 150 and the polishing apparatuses 1A-1 and 1A-2, which are arranged in a side-by-side configuration, as shown in FIG. 7.

The first polishing apparatus 1A-1 is situated or orientated such that the first wafer load-unload station 15 a, the first polishing surface 10 a and the third polishing surface 10 c of the polishing apparatus 1A-1 are closer to the wafer transfer device 50 than the second wafer load-unload station 15 b, the third wafer load-unload station 15 c and the second polishing surface 10 b of the first polishing apparatus, as shown in FIG. 7. Similarly, the second polishing apparatus 1A-2 is situated or orientated such that the first wafer load-unload station 15 a, the first polishing surface 10 a and the third polishing surface 10 c of the polishing apparatus 1A-2 are closer to the wafer transfer device 50 than the second wafer load-unload station 15 b, the third wafer load-unload station 15 c and the second polishing surface 10 b of the second polishing apparatus. In an embodiment, the polishing apparatuses 1A-1 and 1A-2 are orientated such that the first and third polishing surfaces 10 a and 10 c of the first and second polishing apparatuses are linearly arranged to be parallel to the linear track 55 on which the wafer transfer device 50 is mounted.

By this arrangement of the polishing apparatuses 1A-1 and 1A-2, one or more users can have access to every polishing surface of the polishing apparatuses 1A-1 and 1A-2 in the service area to service any polishing surface of the polishing apparatuses 1A-1 and 1A-2, which may involve maintaining the polishing surfaces and changing polishing pads associated with the polishing surfaces. As illustrated in FIG. 7, a user 110 can have access to the second polishing surface 10 b of the first polishing apparatus 1A-1, a user 111 can have access to the second polishing surface 10 b of the second polishing apparatus 1A-2, a user 112 can have access to the first polishing surface 10 a of the first polishing apparatus 1A-1, a user 113 can have access to the third polishing surface 10 c of the first polishing apparatus 1A-1 and the first polishing surface 10 a of the second polishing apparatus 1A-2 at a space between the third wafer load-unload station 15 c of the first polishing apparatus 1A-1 and the second wafer load-unload station 15 b of the second polishing apparatus 1A-2 and between the third polishing surface 10 c of the first polishing apparatus 1A-1 and the first polishing surface 10 a of the second polishing apparatus 1A-2, and a user 114 can have access to the third polishing surface 10 c of the second polishing apparatus 1A-2 at a space between the third wafer load-unload station 15 c and the wall 125.

The wafer cassette unit 105 is used to store wafers that will be polished in the polishing system 100 and to store the wafers that have been polished in the polishing system. The wafer transfer device 110 operates to transfer wafers from the wafer cassette unit 105 to the buffer station 120 and to transfer wafers from the post-CMP cleaner 150 to the wafer cassette unit 105. The buffer station 120 is used to temporarily hold a wafer from the wafer cassette unit 105 that will be polished. The wafer transfer device 50 operates to transfer wafers from the buffer station 120 to the first wafer load-unload stations 15 a of the first and second polishing apparatuses 1A-1 and 1A-2. The wafer transfer device 50 also operates to transfer wafers from the first wafer load-unload stations 15 a of the first and second polishing apparatus 1A-1 and 1A-2 to the post-CMP cleaner 150.

The first and second polishing apparatuses 1A-1 and 1A-2 operate to process the received wafers according to the method described above with respect to the polishing apparatus 1A of FIGS. 1-3. A first set of wafers are processed in the first polishing apparatus 1A-1 and then sent to the post-CMP cleaner 150 by the wafer transfer device 50. A second set of wafers are processed in the second polishing apparatus 1A-2 and then sent to the post-CMP cleaner 150 by the wafer transfer device 50. In an embodiment, the first set of wafers includes every other wafer starting from the first wafer that is transferred from the buffer station 120, and the second set of wafers includes every other wafer starting from the second wafer that is transferred from the buffer station 120.

The post-CMP cleaner 150 operates to clean the wafers that have been polished in the polishing apparatuses 1A-1 and 1A-2. The post-CMP cleaner 150 includes an input station 152, a cleaning station 153 and a drying station 154. In operation, the post-CMP cleaner 150 receives polished wafers transferred by the wafer transfer device 50 at the input station 152, cleans the wafers at the cleaning station 153 and then dries the wafers at the drying station 154. The dried wafers are then transferred to the wafer cassette unit 105 by the wafer transfer device 110.

In the illustrated embodiment, the wafer transfer devices 50 and 110 are single arm devices. That is, each of the wafer transfer devices 50 and 110 includes a single robotic arm to hold and transfer one wafer at a time. In other embodiments, one or both of the wafer transfer devices 50 and 110 may be dual arm devices. In an embodiment in which the wafer transfer device 110 includes dual arms, a first arm of the wafer transfer device 110 may be used exclusively to transfer wafers from the wafer cassette unit 105 to the buffer station 120, and a second arm of the wafer transfer device 110 may be used exclusively to transfer wafers from the drying station 154 of the post-CMP cleaner 150 to the wafer cassette unit 105. Similarly, in an embodiment in which the wafer transfer device 50 includes dual arms, a first arm of the wafer transfer device 50 may be used exclusively to transfer wafers from the buffer station 120 to the first wafer load-unload stations 15 a of the polishing apparatuses 1A-1 and 1A-2, and a second arm of the wafer transfer device 50 may be used exclusively to transfer wafers from the first wafer load-unload stations 15 a of the polishing apparatuses 1A-1 and 1A-2 to the input station 152 of the post-CMP cleaner 150. Furthermore, in some embodiments, the first arm of the wafer transfer device 110 may have a flipping mechanism such that the first arm can flip the wafers before unloading them onto the buffer station 120. Similarly, in some embodiments, the second arm of the wafer transfer device 50 may have a flipping mechanism such that the second arm can flip the wafers before unloading them onto the input station 152 of the post-CMP cleaner 150.

Turning now to FIGS. 8 and 9, a polishing apparatus 1B in accordance with another embodiment of the invention is shown. FIG. 8 is a top view of the polishing apparatus 1B. FIG. 9 is a partial side view of the polishing apparatus 1B of FIG. 8. The polishing apparatus 1B is similar to the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIGS. 8 and 9. The polishing apparatus 1B includes all the elements of the polishing apparatus 1A, and further includes a first washing arm 51 a, a second washing arm 51 b and a third washing arm 51 c, which operate to treat the polishing surfaces 10 a-10 c and the wafer load-unload stations 15 a-15 c with fluid, such as DI water and/or chemicals, in order to remove slurry residue or polishing by-products. The first, second and third washing arms 51 a-51 c are part of a rotation assembly 12B, as illustrated in FIG. 8.

In the illustrated embodiment, one of the ends of the first washing arm 51 a is connected to the rotational shaft 30 between the first supporting arm 45 a and the second supporting arm 45 b such that the first washing arm 51 a extends radially from the rotational shaft 30. The first washing arm 51 a is of sufficient length so that the other end of the first washing arm 51 a can reach at least the center of the first polishing surface 10 a, as shown in FIG. 8. As shown in FIG. 9, the first washing arm 51 a includes spray nozzles 52 that can spray DI water and/or chemicals downward. Thus, the first washing arm 51 a can be used to treat the first polishing surface 10 a with DI water and/or chemicals in order to remove slurry residue or polishing by-products on the first polishing surface 10 a when the first washing arm 51 a is positioned over the first polishing surface 10 a.

Similarly, one of the ends of the second washing arm 51 b is connected to the rotational shaft 30 between the second supporting arm 45 b and the third supporting arm 45 c such that the second washing arm 51 b extends radially from the rotational shaft 30. The second washing arm 51 b is of sufficient length so that the other end of the second washing arm 51 b can reach at least the center of the second polishing surface 10 b, as shown in FIG. 8. The second washing arm 51 b also includes spray nozzles (not shown), such as the spray nozzles 52 of the first washing arm 51 a, that can spray DI water and/or chemicals downward. Thus, the second washing arm 51 b can be used to treat the second polishing surface 10 b with DI water and/or chemicals in order to remove slurry residue or polishing by-products on the second polishing surface 10 b when the second washing arm 51 b is positioned over the second polishing surface 10 b.

Similarly, one of the ends of the third washing arm 51 c is connected to the rotational shaft 30 between the third supporting arm 45 c and the first supporting arm 45 a such that the third washing arm 51 c extends radially from the rotational shaft 30. The third washing arm 51 c is of sufficient length so that the other end of the third washing arm 51 c can reach at least the center of the third polishing surface 10 c, as shown in FIG. 8. The third washing arm 51 c also includes spray nozzles (not shown), such as the spray nozzles 52 of the first washing arm 51 a, that can spray DI water and/or chemicals downward. Thus, the third washing arm 51 c can be used to treat the third polishing surface 10 c with DI water and/or chemicals in order to remove slurry residue or polishing by-products on the third polishing surface 10 c when the third washing arm 51 c is positioned over the third polishing surface 10 c.

As shown in FIG. 10, when the rotational shaft 30 is rotated such that the first, second and third polishing heads 20 a-20 c are rotated in unison and positioned over the first, second and third polishing surfaces 10 a-10 c, respectively, the first, second and third washing arms 51 a-51 c are also rotated in unison and positioned over the second, third and first wafer load-unload stations 15 b, 15 c and 15 a, respectively. Thus, the first, second and third washing arms 51 a-51 c can be used to wash the respective wafer load-unload stations 15 a-15 c using fluid, such as DI water and/or chemicals.

In other embodiments, the first, second and third washing arms 51 a-51 c can be connected to a second rotational shaft (now shown) that is coupled to a second rotational-and-vertical drive mechanism (not shown) instead of being connected to the rotational shaft 30. Thus, the rotational and vertical motions of the second rotational shaft are controlled independently from the first rotational shaft 30. Consequently, the movements of the first, second and third washing arms 51 a-51 c can be independent from the movements of the first, second and third polishing heads 20 a-20 c.

Turning now to FIG. 11, a polishing apparatus 1C in accordance with another embodiment of the invention is shown. FIG. 11 is a top view of the polishing apparatus 1C. The polishing apparatus 1C is similar to the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIG. 11. In the polishing apparatus 1C, the second and third wafer load-unload stations 15 b and 15 c of the polishing apparatus 1A are replaced by first and second wafer washing stations 15 b′ and 15 c′. The wafer washing stations 15 b′ and 15 c′ includes spray nozzles, such as the spray nozzles of the wafer load-unload station 15′, that can spray fluid, such as DI water or chemicals, to wash the polishing heads and the wafers when they are positioned at the wafer washing stations. As stated above, the wafer load-unload station 15 a may be configured to also wash the polishing heads and the wafers when they are positioned at the wafer load-unload station 15 a.

Even though the polishing apparatus 1C is described herein as having three polishing surfaces 10 a-10 c, three polishing heads 20 a-20 c, one wafer load-unload station 15 a, and two wafer washing station 15 b′ and 15 c′, the polishing apparatus 1C according different embodiments of the invention can have different numbers of polishing heads, polishing surfaces, wafer load-unload stations and wafer washing stations. In general, the polishing apparatus 1C comprises N polishing heads, N polishing surfaces, one wafer load-unload station and N−1 wafer washing stations, where N is an integer larger than one. Although not shown, the polishing apparatus 1C may further include washing arms, such as the washing arms 51 a-51 c of the polishing apparatus 1B, to treat the polishing surfaces 10 a-10 c, the wafer load-unload station 15 a, and the washing stations 15 b′ and 15 c′ with fluid, such as DI water and/or chemicals, in order to remove slurry residue or polishing by-products.

With reference to FIG. 11, a method of processing wafers in the polishing apparatus 1C in accordance with an embodiment of the invention is described. A first wafer W1 to be processed is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The first wafer W1 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. After being loaded onto the first polishing head 20 a, the first wafer W1 is transferred from the first wafer load-unload station 15 a to the first polishing surface 10 a by rotationally moving the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a. After this rotational movement, the polishing heads 20 a-20 c are positioned over the polishing surfaces 10 a-10 c, respectively. After the first wafer W1 is removed from the first wafer load-unload station 15 a, a second wafer W2 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a.

After the polishing process is completed, the first, second and third polishing heads 20 a-20 c are rotationally moved in unison to the first washing station 15 b′, the second washing station 15 c′ and the first load-unload station 15 a, respectively, thereby transferring the first wafer W1 from the first polishing surface 10 a to the first washing station 15 b′. The first polishing head 20 a and the first wafer W1 are then washed at the first washing station 15 b′. At the first and second washing stations 15 b′ and 15 c′, wafers are not unloaded onto the washing stations. The second wafer W2 is also loaded onto the third polishing head 20 c from the wafer load-unload station 15 a.

The first, second and third polishing heads 20 a-20 c are then rotationally moved to the second, third and first polishing surfaces 10 b, 10 c and 10 a, respectively. After the second wafer W2 is removed from the first wafer load-unload station 15 a, a third wafer W3 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50.

The first wafer W1 is then polished on the second polishing surface 10 b by the first polishing head 20 a. This polishing process of the first wafer W1 on the second polishing surface 10 b involves rotating and pressing the first wafer W1 on the second polishing surface 10 b by the first polishing head 20 a, rotating the second polishing surface 10 b and supplying a second slurry to the second polishing surface 10 b.

The second wafer W2 is also polished on the first polishing surface 10 a by the third polishing head 20 c. This polishing process of the second wafer W2 on the first polishing surface 10 a involves rotating and pressing the second wafer W2 on the first polishing surface 10 a by the third polishing head 20 c, rotating the first polishing surface 10 a and supplying the first slurry to the first polishing surface 10 a.

After the polishing processes are completed, the first, second and third polishing heads 20 a-20 c are rotationally moved to the second washing station 15 c′, the first load-unload station 15 a and the first washing station 15 b′, respectively, thereby transferring the first wafer W1 from the second polishing surface 10 b to the second washing station 15 c′ and transferring the second wafer W2 from the first polishing surface 10 a to the first washing station 15 b′. The first polishing head 20 a and the first wafer W1 are then washed at the second washing station 15 c′. The third polishing head 20 c and the second wafer W2 are also washed at the first washing station 15 b′. The third wafer W3 is also loaded onto the second polishing head 20 b from the wafer load-unload station 15 a.

The first, second and third polishing heads 20 a-20 c are then rotationally moved to the third, first and second polishing surfaces 10 c, 10 a and 10 b, respectively.

The first wafer W1 is then polished on the third polishing surface 10 c by the first polishing head 20 a. This polishing process of the first wafer W1 on the third polishing surface 10 c involves rotating and pressing the first wafer W1 on the third polishing surface 10 c by the first polishing head 20 a, rotating the third polishing surface 10 c and supplying a third slurry to the third polishing surface 10 c.

The second wafer W2 is also polished on the second polishing surface 10 b by the third polishing head 20 c. This polishing process of the second wafer W2 on the second polishing surface 10 b involves rotating and pressing the second wafer W2 on the second polishing surface 10 b by the third polishing head 20 c, rotating the second polishing surface 10 b and supplying the second slurry to the second polishing surface 10 b.

The third wafer W1 is also polished on the first polishing surface 10 a by the second polishing head 20 b. This polishing process of the third wafer W3 on the first polishing surface 10 a involves rotating and pressing the third wafer W3 on the first polishing surface 10 a by the second polishing head 20 b, rotating the first polishing surface 10 a and supplying the first slurry to the first polishing surface 10 a.

After the polishing processes are completed, the first, second and third polishing heads 20 a-20 c are rotationally moved to the first wafer load-unload station 15 a, the first washing station 15 b′ and the second washing station 15 c′, respectively, thereby transferring the first wafer W1 from the third polishing surface 10 c to the first wafer load-unload station 15 a, transferring the second wafer W2 from the second polishing surface 10 b to the second washing station 15 c′ and transferring the third wafer W3 from the first polishing surface 10 a to the first washing station 15 b′.

The first wafer W1 is then unloaded onto the first load-unload station 15 a. The first polishing head 20 a and the first wafer W1 may be washed at the wafer load-unload station 15 a. The first wafer W1 is then removed from the first load-unload station 15 a by the wafer transfer device 50. After the first wafer W1 is removed from the first wafer load-unload station 15 a, a fourth wafer W4 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The third polishing head 20 c and the second wafer W2 are washed at the second washing station 15 c′. The second polishing head 20 b and the third wafer W3 are also washed at the first washing station 15 b′.

During the washing processes at the wafer load-unload station 15 a, the first washing station 15 b′ and the second washing station 15 c′, the polishing surfaces 10 a-10 c can be simultaneously washed using the washing arms 51 a-51 c.

In this sequential manner, wafers can be processed continuously through the polishing surfaces 10 a-10 c of the polishing apparatus 1C. A first group of wafers are polished on the polishing surfaces 10 a-10 c using exclusively the first polishing head 20 a. Similarly, a second group of wafers are polished on the polishing surfaces 10 a-10 c using exclusively the third polishing head 20 c. Similarly, a third group of the wafers are polished on the polishing surfaces 10 a-10 c using exclusively the second polishing head 20 b. In an embodiment, the first set of wafers includes every third wafer starting from the first wafer, the second set of wafers includes every third wafer starting from the second wafer, and the third set of wafers includes every third wafer starting from the third wafer.

With reference to FIGS. 12-14, a polishing apparatus 1D according to another embodiment of the invention is described. FIGS. 12 and 13 are top views of the polishing apparatus 1D, while FIG. 14 is a partial side view of the polishing apparatus 1D. The polishing apparatus 1D is similar to the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIG. 12-14. The polishing apparatus 1D includes all the elements of the polishing apparatus 1A, and further includes a pivoting wafer transfer device 121.

The pivoting wafer transfer device 121 includes a wafer load-unload cup 122, which is connected to a rotational shaft 126 through an arm 124. The shaft 126 is coupled to a pivoting-and-vertical drive mechanism 128, which controls pivoting and vertical motions of the wafer load-unload cup 122. The wafer load-unload cup 122 may be similar to the wafer load-unload station 15′.

The pivoting wafer transfer device 121 operates to pivot the wafer load-unload cup 122 between a parking position X and a wafer transfer position Y, as shown in FIGS. 12 and 13. FIG. 12 is a top view of the polishing apparatus 1D when the wafer load-unload cup 122 is positioned at the parking position X. FIG. 13 is a top view of the polishing apparatus 1D when the wafer load-unload cup 122 is positioned at the wafer transfer position Y, which is located over the first wafer load-unload station 15 a.

At the parking position X, the wafer load-unload cup 122 is able to transfer wafers with the wafer transfer device 50, as illustrated in FIG. 12. At the wafer transfer position Y, the wafer load-unload cup 122 is able to transfer with any of the polishing heads 20 a-20 c, when that polishing head is positioned over the wafer transfer position Y, as illustrated in FIGS. 13 and 14. FIG. 14 shows a partial side view of the polishing apparatus 1D when the wafer load-unload cup 122 is positioned at the wafer transfer position Y and the polishing head 20 a is positioned over the wafer transfer position Y.

With reference FIGS. 12 and 13, a first method of processing wafers in the polishing apparatus 1D in accordance with an embodiment of the invention is described. A first wafer W1 to be processed is transferred to and unloaded onto the wafer load-unload cup 122 of the pivoting wafer transfer device 121 at the parking position X, by the wafer transfer device 50, as illustrated in FIG. 12. The wafer load-unload cup 122 is then pivoted to the wafer transfer position Y by the pivoting-and-vertical drive mechanism 128, as illustrated in FIG. 13.

At the wafer transfer position Y, the first wafer W1 is then loaded onto the first polishing head 20 a from the wafer load-unload cup 122 of the pivoting wafer transfer device 121. After the first wafer W1 is removed from the wafer load-unload cup 122, the wafer load-unload cup 122 is pivoted back to the parking position X to receive the next wafer. The first wafer W1 is then transferred from the wafer transfer position Y to the first polishing surface 10 a by rotationally moving the first polishing head 20 a.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a. The first wafer W1 is then further processed in the polishing apparatus 1D in the same manner as in the polishing apparatus 1A. The subsequent wafers are sequentially processed in the same manner as the first wafer W1.

In this sequential manner, wafers are processed continuously through the polishing surfaces 10 a-10 c using the polishing heads 20 a-20 c. This sequential manner is similar to the sequential manner of processing wafers in the polishing apparatus 1A except that the wafers that will be polished in the polishing apparatus 1D are supplied to the first polishing head 20 a by the wafer load-unload cup 122 at the wafer transfer position Y over the first wafer load-unload station 15 a.

With reference to FIGS. 12 and 13, a second method of processing wafers in the polishing apparatus 1D in accordance with an embodiment of the invention is described. In this method, wafers to be processed are sequentially unloaded onto the wafer load-unload station 15 a by the wafer transfer device 50 and processed in the same manner as in the polishing apparatus 1A, up to and including the polishing of the wafers on the polishing surface 10 c.

However, after the polishing process on the polishing surface 10 c is completed, each polished wafer is transferred to the wafer transfer position Y over the first wafer load-unload station 15 a by rotationally moving the third polishing head 20 c. The wafer is then unloaded onto the wafer load-unload cup 122 of the pivoting wafer transfer device 121 at the wafer transfer position Y. The wafer load-unload cup 122 is then pivoted to the parking position X, thereby transferring the wafer to the parking position X. In addition, the third polishing head 20 c is rotationally moved back to the third wafer load-unload station 15 c to further process the next wafer. The wafer on the wafer load-unload cup 122 is then removed from the wafer load-unload cup 122 at the parking position X by the wafer transfer device 50. Subsequent wafers are sequentially processed in the same manner.

In this sequential manner, wafers are processed continuously through the polishing surfaces 10 a-10 c using the polishing heads 20 a-20 c. This sequential manner is similar to the sequential manner of processing wafers in the polishing apparatus 1A except that the wafers polished in the polishing apparatus 1D are removed from the third polishing head 20 c to the wafer load-unload cup 122 at the wafer transfer position Y over the first wafer load-unload station 15 a.

With reference to FIGS. 12 and 13, a third method of processing wafers in the polishing apparatus 1D in accordance with an embodiment of the invention is described. A first wafer W1 to be processed is transferred to and unloaded onto the wafer load-unload cup 122 of the pivoting wafer transfer device 121 at the parking position X, by the wafer transfer device 50, as illustrated in FIG. 12. The wafer load-unload cup 122 is then pivoted to the wafer transfer position Y by the pivoting-and-vertical drive mechanism 128, as illustrated in FIG. 13.

At the wafer transfer position Y, the first wafer W1 is then loaded onto the first polishing head 20 a from the wafer load-unload cup 122 of the pivoting wafer transfer device 121. After the first wafer W1 is removed from the wafer load-unload cup 122, the wafer load-unload cup 122 is pivoted back to the parking position X to receive the next wafer to be processed. The first wafer W1 is transferred from the wafer transfer position Y to the first polishing surface 10 a by rotationally moving the first polishing head 20 a.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a.

After the polishing process is completed, the first polishing head 20 a is rotationally moved to the second wafer load-unload station 15 b. The first polishing head 20 a and the first wafer W1 are washed with DI water and/or chemicals at the second wafer load-unload station 15 b. The first polishing head 20 a is then rotationally moved to the second polishing surface 10 b. For this third method, the second wafer load-unload station 15 b can be replaced with the first wafer washing station 15 b′ of the polishing apparatus 1C since wafers do not have to be unloaded and loaded at the second wafer load-unload station 15 b.

The first wafer W1 is then polished on the second polishing surface 10 b by the first polishing head 20 a. This polishing process of the first wafer W1 on the second polishing surface 10 b involves rotating and pressing the first wafer W1 on the second polishing surface 10 b by the first polishing head 20 a, rotating the second polishing surface 10 b and supplying a second slurry to the second polishing surface 10 b.

After the polishing process is completed, the first polishing head 20 a is rotationally moved to the third wafer load-unload station 15 c. The first polishing head 20 a and the first wafer W1 are washed with DI water and/or chemicals at the third wafer load-unload station 15 c. The first polishing head 20 a is then rotationally moved to the third polishing surface 10 c. For this third method, the third wafer load-unload station 15 c can be replaced with the second wafer washing station 15 c′ of the polishing apparatus 1C since wafers do not have to be unloaded and loaded at the third wafer load-unload station 15 c.

The first wafer W1 is then polished on the third polishing surface 10 c by the first polishing head 20 a. This polishing process of the first wafer W1 on the third polishing surface 10 c involves rotating and pressing the first wafer W1 on the third polishing surface 10 c by the first polishing head 20 a, rotating the third polishing surface 10 c and supplying a third slurry to the third polishing surface 10 c.

After the polishing process is completed, the first wafer W1 is transferred to the first wafer load-unload station 15 a by rotationally moving the first polishing head 20 a. The first wafer W1 is then unloaded onto the first wafer load-unload station 15 a from the first polishing head 20 a. The first wafer W1 is removed from the first wafer load-unload station 15 a by the wafer transfer device 50. Subsequent wafers are sequentially processed in the same manner as the first wafer W1 using one of the polishing heads 20 a-20 c on a rotational basis. Thus, the next wafer is processed using the polishing head 20 c.

In this sequential manner, wafers are processed continuously through the polishing surfaces 10 a-10 c using a particular polishing head for each of the wafers. This sequential manner is similar to the sequential manner of processing wafers in the polishing apparatus 1D according to the first method except that the wafers polished in the polishing apparatus 1D are processed by dedicated polishing heads in this third method. A first group of wafers are polished on the polishing surfaces 10 a-10 c using exclusively the first polishing head 20 a. Similarly, a second group of wafers are polished on the polishing surfaces 10 a-10 c using exclusively the third polishing head 20 c. Similarly, a third group of the wafers are polished on the polishing surfaces 10 a-10 c using exclusively the second polishing head 20 b. In an embodiment, the first set of wafers includes every third wafer starting from the first wafer, the second set of wafers includes every third wafer starting from the second wafer, and the third set of wafers includes every third wafer starting from the third wafer.

With reference to FIGS. 12 and 13, a fourth method of processing wafers in the polishing apparatus 1D in accordance with an embodiment is described. A first wafer W1 to be processed is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The first wafer W1 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. After being loaded onto the first polishing head 20, the first wafer W1 is transferred from the first wafer load-unload station 15 a to the first polishing surface 10 a by rotationally moving the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a. The first wafer W1 is then processed in the same manner as the third method of processing wafers in the polishing apparatus 1D up to and including the polishing process on the third polishing surface 10 c.

After the polishing process is completed at the polishing surface 10 c, the first polishing head 20 a is rotationally moved to the wafer transfer position Y over the first wafer load-unload station 15 a. The wafer load-unload cup 122 is also pivoted to the wafer transfer position Y. The first wafer W1 is then unloaded from the first polishing head 20 a onto the wafer load-unload cup 122 at the wafer transfer position Y. After the first wafer W1 is unloaded onto the wafer load-unload cup 122, the wafer load-unload cup 122 is pivoted to the parking position X, where the first wafer W1 is removed from the wafer load-unload cup 122 by the wafer transfer device 50. Subsequent wafers are sequentially processed in the same manner as the first wafer W1 using one of the polishing heads 20 a-20 c on a rotational basis.

In this sequential manner, wafers are processed continuously through the polishing surfaces 10 a-10 c using a particular polishing head for each of the wafers. This sequential manner is similar to the sequential manner of processing wafers in the polishing apparatus 1D according to the second method except that the wafers polished in the polishing apparatus 1D are processed by dedicated polishing heads.

Turning now to FIGS. 15-17, a polishing apparatus 1E in accordance with another embodiment of the invention is shown. FIGS. 15 and 16 are top views of the polishing apparatus 1E, while FIG. 17 is a partial side view of the polishing apparatus 1E. The polishing apparatus 1E is similar to the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIGS. 15-17. The polishing apparatus 1E includes all the elements of the polishing apparatus 1A, and further includes head pivoting mechanisms 27 a-27 c and pivoting arms 47 a-47 c, which allow the polishing heads 20 a-20 c to be independently pivoted, as described below. The head pivoting mechanisms 27 a-27 c and the pivoting arms 47 a-47 c are part of a rotation assembly 12E, as illustrated in FIGS. 15 and 16.

As shown in FIGS. 15 and 16, the head pivoting mechanisms 27 a-27 c are connected to the supporting arms 45 a-45 c, respectively, and also connected to the pivoting arms 47 a-47 c, respectively. The pivoting arms 47 a-47 c are connected to the rotational-and-vertical drive mechanism 25 a-25 c, respectively, which are coupled to their respectively polishing heads 20 a-20 c. Thus, the polishing heads 20 a-20 c can be independently pivoted about pivoting axes 48 a-48 c, respectively, by the head pivoting mechanisms 27 a-27 c by independently pivoting the pivoting arms 47 a-47 c, in addition to being rotationally moved about the rotational axis 36 by the central rotational-and-vertical drive mechanism 35, as illustrated in FIG. 17.

With reference to FIG. 15, a method of processing wafers in the polishing apparatus 1E in accordance with an embodiment of the invention is described. FIG. 15 shows the polishing apparatus 1E when the first head pivoting mechanism 27 a is positioned between the first wafer load-unload station 15 a and the first polishing surface 10 a, the second head pivoting mechanism 27 b is positioned between the second wafer load-unload station 15 b and the second polishing surface 10 b and the third head pivoting mechanism 27 c is positioned between the third wafer load-unload station 15 c and the third polishing surface 10 c. In some embodiments, the second and third wafer load-unload stations 15 b and 15 c can be replaced with the first and second washing stations 15 b′ and 15 c′, respectively, of the polishing apparatus 1C.

At the position shown in FIG. 15, the first head pivoting mechanism 27 a can transfer the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a by pivoting the first polishing head 20 a about the pivoting axis 48 a along a curved direction A without rotating the rotational shaft 30 about the rotational axis 36. Similarly, the second head pivoting mechanism 27 b can transfer the second polishing head 20 b from the second wafer load-unload station 15 b to the second polishing surface 10 b by pivoting the second polishing head 20 b about the pivoting axis 48 b along a curved direction B without rotating the rotational shaft 30 about the rotational axis 36. Similarly, the third head pivoting mechanism 27 c can transfer the third polishing head 20 c from the third wafer load-unload station 15 c to the third polishing surface 10 c by pivoting the third polishing head 20 c about the pivoting axis 48 c along a curved direction C without rotating the rotational shaft 30 about the rotational axis 36.

Therefore, it is possible to move the polishing heads 20 a-20 c individually from their respective wafer load-unload stations 15 a-15 c to the adjacent polishing surfaces 10 a-10 c such that the polishing heads 20 a-20 c can start polishing processes on their respective polishing surfaces individually as soon as the polishing heads 20 a-20 c are ready to do so.

In some embodiments, each wafer can be processed in the polishing apparatus 1E using the polishing heads 20 a-20 c in a manner similar to the method described above with respect to the polishing apparatus 1A. In other embodiments, each wafer can be processed in the polishing apparatus 1E using one of the polishing heads 20 a-20 b in a manner similar to the method described above with respect to the polishing apparatus 1C.

With reference to FIG. 16, another method of processing wafers in the polishing apparatus 1E in accordance with an embodiment of the invention is described. FIG. 16 shows the polishing apparatus 1E when the first head pivoting mechanism 27 a is positioned between the first polishing surface 10 a and the second wafer load-unload station 15 b, the second head pivoting mechanism 27 b is positioned between the second polishing surface 10 b and the third wafer load-unload station 15 c and the third head pivoting mechanism 27 c is positioned between the third polishing surface 10 c and the first wafer load-unload station 15 a. As previously mentioned, in some embodiments, the second and third wafer load-unload stations 15 b and 15 c can be replaced with the first and second washing stations 15 b′ and 15 c′, respectively, of the polishing apparatus 1C.

At the position shown in FIG. 16, the first head pivoting mechanism 27 a can transfer the first polishing head 20 a from the first polishing surface 10 a to the second wafer load-unload station 15 b by pivoting the first polishing head 20 a about the pivoting axis 48 a along a curved direction A′ without rotating the rotational shaft 30 about the rotational axis 36. Similarly, the second head pivoting mechanism 27 b can transfer the second polishing head 20 b from the second polishing surface 10 b to the third wafer load-unload station 15 c by pivoting the second polishing head 20 b about the pivoting axis 48 b along a curved direction B′ without rotating the rotational shaft 30 about the rotational axis 36. Similarly, the third head pivoting mechanism 27 c can transfer the third polishing head 20 c from the third polishing surface 10 c to the first wafer load-unload station 15 a by pivoting the third polishing head 20 c about the pivoting axis 48 c along a curved direction C′ without rotating the rotational shaft 30 about the rotational axis 36.

Therefore, it is possible to move the polishing heads 20 a-20 c individually from their respective polishing surfaces 10 a-10 c to the adjacent wafer load-unload stations 15 a-15 c such that the unloading or washing processes can be individually initiated at the respective wafer load-unload stations as soon as the polishing processes are finished at the polishing surfaces.

In some embodiments, each wafer can be processed in the polishing apparatus 1E using the polishing heads 20 a-20 c in a manner similar to the method described above with respect to the polishing apparatus 1A. In other embodiments, each wafer can be processed in the polishing apparatus 1E using one of the polishing heads 20 a-20 b in a manner similar to the method described above with respect to the polishing apparatus 1C.

Turning now to FIG. 18, a polishing apparatus 1F in accordance with another embodiment of the invention is shown. The polishing apparatus 1F includes some of the elements of the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIG. 18. As shown in FIG. 18, the polishing apparatus 1F includes two polishing surfaces 10 a and 10 b, and two polishing heads 20 a and 20 b and two wafer load-unload stations 15 a and 15 b. The polishing heads 20 a and 20 b are part of a rotation assembly 12F that includes only two supporting arms 45 a and 45 b, which are attached to the rotational shaft 30, and two rotational-and-vertical drive mechanisms 25 a and 25 b, which are coupled to the polishing heads 20 a and 20 b, respectively. Thus, the polishing heads 20 a and 20 b are rotationally moved in unison when the rotational shaft 30 is rotated.

In this embodiment, the polishing surfaces 10 a and 10 b are linearly aligned with the rotational axis 36 of the rotation assembly 12F along the X axis. As an example, the polishing surfaces 10 a and 10 b are positioned such that the centers of the polishing surfaces and the rotational axis 36 define a straight line 11 a parallel to the X axis, as illustrated in FIG. 18. In addition, the wafer load-unload stations 15 a and 15 b are linearly aligned with the rotational axis 36 of the rotation assembly 12 along the Y axis. As an example, the wafer load-unload stations 15 a and 15 b are positioned such that the centers of the wafer load-unload stations and the rotational axis 36 define a straight line 11 b parallel to the Y axis, as illustrated in FIG. 18. Thus, the lines 11 a and 11 b are perpendicular to each other. That is, the angle α between the lines 11 a and 11 b is ninety degrees.

In an alternative embodiment, the wafer load-unload stations 15 a and 15 b are positioned such that the line 11 b defined by the centers of the wafer load-unload stations and the rotational axis 36 is not parallel to the Y axis, as illustrated in FIG. 19. Thus, in this alternative embodiment, the angle α between the lines 11 a and 11 b is greater than ninety degrees. This arrangement of the wafer load-unload stations 15 a and 15 b reduces the footprint of the polishing apparatus 1F along the Y axis.

The polishing apparatus 1A of FIG. 1 has been described as having three polishing surfaces 10 a-10 c, three polishing heads 20 a-20 c, and three wafer load-unload stations 15 a-15 c. The polishing apparatus 1F of FIG. 18 has been described as having two polishing surfaces 10 a and 10 b, two polishing heads 20 a and 20 b, and two wafer load-unload stations 15 a and 15 b. However, the polishing apparatuses 1A and 1F according different embodiments of the invention can have different numbers of polishing heads, polishing surfaces, and wafer load-unload stations. In general, the polishing apparatuses 1A and 1F can comprise N polishing heads that are connected to a rotational shaft, N polishing surfaces, N wafer load-unload stations, where N is an integer larger than one. The N polishing surfaces may be equally spaced to each other around the rotational shaft. The N wafer load-unload stations may be equally spaced to each other around the rotational shaft.

With reference to FIGS. 18 and 19, a method of processing wafers in the polishing apparatus 1F in accordance with an embodiment of the invention is described. In this embodiment, the rotation assembly 12F is configured to rotationally move the polishing heads 20 a and 20 b such that the first polishing head 20 a can be moved exclusively between the first wafer load-unload station 15 a, the first polishing surface 20 a and the second wafer load-unload station 15 b, and the second polishing head 20 b can be moved exclusively between the second wafer load-unload station 15 b, the second polishing surface 20 b and the first wafer load-unload station 15 a.

Initially, the polishing heads 20 a and 20 b are positioned over the first and second wafer load-unload stations 15 a and 15 b, respectively. A first wafer W1 to be processed is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The first wafer W1 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. After the first wafer W1 is loaded onto the first polishing head 20 a, the first wafer W1 is transferred from the first wafer load-unload station 15 a to the first polishing surface 10 a by rotationally moving the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a. After this movement, the polishing heads 20 a and 20 b are positioned over the polishing surfaces 10 a and 10 b, respectively, as illustrated in FIGS. 18 and 19. After the first wafer W1 is removed from the first wafer load-unload station 15 a, a second wafer W2 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50 to be processed in the same manner as the first wafer W1.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a.

After the polishing process is completed, the first wafer W1 is transferred from the first polishing surface 10 a to the second wafer load-unload station 15 b by rotationally moving the first polishing head 20 a from the first polishing surface 10 a to the second wafer load-unload station 15 b. After this movement, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 b and 15 a, respectively.

The first wafer W1 is then unloaded from the first polishing head 20 a onto the second wafer load-unload station 15 b. After the first wafer W1 is unloaded, the first polishing head 20 a is rotationally moved back to the first wafer load-unload station 15 a. After this movement, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 a and 15 b, respectively.

The second wafer W2 is then loaded onto the first polishing head 20 a from the wafer load-unload station 15 a. The first wafer W1 is also loaded onto the second polishing head 20 b from the wafer load-unload station 15 b. The second wafer W2 and the first wafer W1 are then transferred to the first and second polishing surfaces 10 a and 10 b, respectively, by rotationally moving the first and second polishing heads 20 a and 20 b in unison to the first and second polishing surfaces 10 a and 10 b, respectively. After this movement, the polishing heads 20 a and 20 b are positioned over the polishing surfaces 10 a and 10 b, respectively, as illustrated in FIGS. 18 and 19.

The second wafer W2 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the second wafer W2 on the first polishing surface 10 a involves rotating and pressing the second wafer W2 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying the first slurry to the first polishing surface 10 a.

The first wafer W1 is also polished on the second polishing surface 10 b by the second polishing head 20 b. This polishing process of the first wafer W1 on the second polishing surface 10 b involves rotating and pressing the first wafer W1 on the second polishing surface 10 b by the second polishing head 20 b, rotating the second polishing surface 10 b and supplying a second slurry to the second polishing surface 10 b.

After the polishing processes are completed, the first and second wafers W1 and W2 are transferred to the first and second wafer load-unload stations 15 a and 15 b, respectively, by rotationally moving the first and second polishing heads 20 a and 20 b. After this movement, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 b and 15 a, respectively.

The second wafer W2 is then unloaded from the first polishing head 20 a onto the second wafer load-unload station 15 b. The first wafer W1 is also unloaded from the second polishing head 20 b onto the first wafer load-unload station 15 a. After the first and second wafers W1 and W2 are unloaded, the first and second polishing heads 20 a and 20 b are rotationally moved back to the first and second wafer load-unload stations 15 a and 15 b, respectively. After this movement, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 a and 15 b, respectively.

Next, the first wafer W1 is removed from the first wafer load-unload station 15 a by the wafer transfer device 50 and a third wafer W3 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The second and third wafers W2 and W3 are processed further in the polishing apparatus 1F of FIG. 18 or 19 in the same sequential manner as the first wafer W1.

In this sequential manner, multiple wafers can be continuously transferred between the wafer load-unload stations 15 a and 15 b and the polishing surfaces 10 a and 10 b of the polishing apparatus 1F, and polished on the polishing surfaces 10 a and 10 b by the polishing heads 20 a and 20 b.

With reference to FIGS. 18 and 19, a method of processing wafers in the polishing apparatus 1F in accordance with another embodiment of the invention is described. In this embodiment, the rotation assembly 12F is configured to rotationally move the polishing heads 20 a and 20 b such that the first and second polishing heads can be continuously moved in a counterclockwise direction from the first wafer load-unload station 15 a to the first polishing surface 20 a and so on.

Initially, the polishing heads 20 a and 20 b are positioned over the first and second wafer load-unload stations 15 a and 15 b, respectively. A first wafer W1 to be processed is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The first wafer W1 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. After the first wafer W1 is loaded onto the first polishing head 20 a, the first wafer W1 is transferred from the first wafer load-unload station 15 a to the first polishing surface 10 a by rotationally moving the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a. After this movement, the polishing heads 20 a and 20 b are positioned over the polishing surfaces 10 a and 10 b, respectively, as illustrated in FIGS. 18 and 19. After the first wafer W1 is removed from the first wafer load-unload station 15 a, a second wafer W2 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50 to be processed.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a.

After the polishing process is completed, the first and second polishing heads 20 a and 20 b are rotationally moved in unison to the wafer load-unload stations 15 b and 15 a, respectively. The first polishing head 20 a and the first wafer W1 are then washed with DI water and/or chemicals at the second wafer load-unload station 15 b. For this method, the second wafer load-unload station 15 b can be replaced with the first wafer washing station 15 b′ of the polishing apparatus 1C since wafers do not have to be unloaded and loaded at the second wafer load-unload station 15 b. Also, the second wafer W2 is loaded onto the second polishing head 20 b from the wafer load-unload station 15 a.

The first and second polishing heads 20 a and 20 b are then rotationally moved in unison to the polishing surfaces 10 b and 10 a, respectively. After this movement, the polishing heads 20 a and 20 b are positioned over the polishing surfaces 10 b and 10 a, respectively.

The first wafer W1 is then polished on the second polishing surface 10 b by the first polishing head 20 a. This polishing process of the first wafer W1 on the second polishing surface 10 b involves rotating and pressing the first wafer W1 on the second polishing surface 10 b by the first polishing head 20 a, rotating the second polishing surface 10 b and supplying a second slurry to the second polishing surface 10 b.

The second wafer W2 is also polished on the first polishing surface 10 a by the second polishing head 20 b. This polishing process of the second wafer W2 on the first polishing surface 10 a involves rotating and pressing the second wafer W2 on the first polishing surface 10 a by the second polishing head 20 b, rotating the first polishing surface 10 a and supplying the first slurry to the first polishing surface 10 a.

After the polishing processes are completed, the first and second wafers W1 and W2 are transferred to the first and second wafer load-unload stations 15 a and 15 b, respectively, by rotationally moving the first and second polishing heads 20 a and 20 b in unison. After this movement, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 a and 15 b, respectively.

The second polishing head 20 b and the second wafer W2 are then washed with DI water and/or chemicals at the second wafer load-unload station 15 b. At the same time, the first wafer W1 is unloaded from the first polishing head 20 a onto the first wafer load-unload station 15 a. The first and second polishing heads 20 a and 20 b are then rotationally moved to the first and second polishing surfaces 10 a and 10 b, respectively. After this movement, the polishing heads 20 a and 20 b are positioned over the first and second polishing surfaces 10 a and 10 b, respectively, as illustrated in FIGS. 18 and 19.

After the first polishing head 20 a has moved away from the first wafer load-unload station 15 a, the first wafer W1 is removed from the first wafer load-unload station 15 a by the wafer transfer device 50 and a third wafer W3 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The second and third wafers W2 and W3 are processed further in the polishing apparatus 1F of FIG. 18 or 19 in the same sequential manner as the first wafer W1.

In this sequential manner, wafers are processed continuously through the polishing surfaces 10 a and 10 b using a particular polishing head for each of the wafers. That is, in this embodiment, wafers are polished in the polishing apparatus 1F by dedicated polishing heads.

In some embodiments, the rotation assembly 12F of the polishing apparatus 1F may include one or more washing arms (not shown), such as the washing arms 51 a-51 c of the polishing apparatus 1B, to treat the polishing surfaces 10 a and 10 b and the wafer load-unload stations 15 a and 15 b with fluid, such as DI water and/or chemicals, as the rotation assembly 12F is rotated about the rotational axis 36 in order to remove slurry residue or polishing by-products. As an example, the rotation assembly 12B of the polishing apparatus 1F may include two washing arms (not shown) attached to the rotational shaft 30 such that the two washing arms are aligned with the line 11 b when the polishing heads 20 a and 20 b are aligned with the line 11 a.

In some embodiments, the wafer load-unload station 15 b of the polishing apparatus 1F may be replaced with a wafer washing station, such as the wafer washing stations 15 b′ and 15 c′ of the polishing apparatus 1C. In these embodiments, each wafer is processed in the polishing apparatus 1F by a dedicated polishing head, either the polishing head 20 a or 20 b. Furthermore, each wafer is not unloaded onto the wafer station 15 b since the same polishing head is used to sequentially polish each wafer on the first and second polishing surfaces 10 a and 10 b. In these embodiments, the wafer station 15 b is used to wash the polishing heads 20 a and 20 b and the wafers being held by the polishing heads when one of the polishing heads is rotationally moved over the wafer station 15 b.

In some embodiments, the rotation assembly 12F of the polishing apparatus 1F may be configured to include head pivoting mechanisms and pivoting arms (not shown), such as the head pivoting mechanisms 27 a-27 c and pivoting arms 47 a-47 c of the polishing apparatus 1E, so that each of the polishing heads 20 a-20 c can be independently pivoted about a respective pivoting axis, as illustrated in FIGS. 15-17. In these embodiments, each wafer can be processed in the polishing apparatus 1F using both the polishing heads 20 a and 20 b or using one of the polishing heads as a dedicated polishing head for that wafer in a manner similar to one of the processing methods described above.

In some embodiments, the polishing apparatus 1F may further include a pivoting wafer transfer device (not shown), such as the pivoting wafer transfer device 121 of the polishing apparatus 1D, to load wafers onto the polishing heads 20 a and 20 b or to unload wafers from the polishing heads at the wafer load-unload station 15 a. Thus, the pivoting wafer transfer device of the polishing apparatus 1F is positioned near the wafer load-unload station 15 a so that the pivoting wafer transfer device can be pivoted over the wafer load-unload station 15 a and also can be pivoted away from the wafer load-unload station 15 a. Similar to the pivoting wafer transfer device 121 of the polishing apparatus 1D, the pivoting wafer transfer device of the polishing apparatus 1F may be used to receive wafers to be polished in the polishing apparatus 1F or to receive wafers that have been polished in the polishing apparatus 1F.

Turning now to FIG. 20, a polishing apparatus 1G according to another embodiment of the invention is shown. The polishing apparatus 1G includes some of the elements of the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIG. 20. As shown in FIG. 20, the polishing apparatus 1G includes two polishing surfaces 10 a and 10 b, two polishing heads 20 a and 20 b and three wafer load-unload stations 15 a-15 c. The polishing heads 20 a and 20 b are part of a rotation assembly 1G that includes only two supporting arms 45 a and 45 b, which are attached to the rotational shaft 30, and two rotational-and-vertical drive mechanisms 25 a and 25 b, which are coupled to the polishing heads 20 a and 20 b, respectively. Thus, the polishing heads 20 a and 20 b are rotationally moved in unison when the rotational shaft 30 is rotated.

The first polishing surface 10 a is positioned between the first and second wafer load-unload stations 15 a and 15 b. The second polishing surface 10 b is positioned between the second and third wafer load-unload stations 15 b and 15 c. The wafer transfer device 50 is situated near the first and third wafer load-unload stations 15 a and 15 c to access both of the wafer load-unload stations 15 a and 15 c.

In some embodiments, the first polishing head 20 a is rotationally moved exclusively between the first wafer load-unload station 15 a, the first polishing surface 10 a and the second wafer load-unload station 15 b. Similarly, the second polishing head 20 b is rotationally moved exclusively between the second wafer load-unload station 15 b, the second polishing surface 10 b and the third wafer load-unload station 15 c. The wafer transfer device 50 operates to provide wafers to be polished to the first wafer load-unload station 15 a and to remove polished wafers from the third wafer load-unload station 15 c.

With reference to FIG. 20, a method of processing wafers in the polishing apparatus 1G in accordance with an embodiment is described. Initially, the polishing heads 20 a and 20 b are positioned over the first and second wafer load-unload stations 15 a and 15 b, respectively, as shown in FIG. 20. A first wafer W1 to be processed is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The first wafer W1 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a and is transferred from the first wafer load-unload station 15 a to the first polishing surface 10 a by rotationally moving the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a. After this movement, the polishing heads 20 a and 20 b are positioned over the polishing surfaces 10 a and 10 b, respectively. After the first wafer W1 is removed from the first wafer load-unload station 15 a, a second wafer W2 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50.

The first wafer W1 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the first wafer W1 on the first polishing surface 10 a involves rotating and pressing the first wafer W1 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying a first slurry to the first polishing surface 10 a.

After the polishing process is completed, the first wafer W1 is transferred from the first polishing surface 10 a to the second wafer load-unload station 15 b by rotationally moving the first polishing head 20 a from the first polishing surface 10 a to the second wafer load-unload station 15 b. As a result, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 b and 15 c, respectively.

The first wafer W1 is then unloaded from the first polishing head 20 a to the second wafer load-unload station 15 b. After the first wafer W1 is unloaded, the first polishing head 20 a is rotationally moved back to the first wafer load-unload station 15 a. After this movement, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 a and 15 b, respectively, as illustrated in FIG. 20.

The second wafer W2 is then loaded onto the first polishing head 20 a from the wafer load-unload station 15 a. The first wafer W1 is also loaded onto the second polishing head 20 b from the wafer load-unload station 15 b. The first and second wafer W1 and W2 are then transferred to the second and first polishing surfaces 10 b and 10 a, respectively, by rotationally moving the first and second polishing heads 20 a and 20 b in unison to the first and second polishing surfaces 10 a and 10 b, respectively. After this movement, the polishing heads 20 a and 20 b are positioned over the polishing surfaces 10 a and 10 b, respectively. After the second wafer W2 is removed from the first wafer load-unload station 15 a, a third wafer W3 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50.

The second wafer W2 is then polished on the first polishing surface 10 a by the first polishing head 20 a. This polishing process of the second wafer W2 on the first polishing surface 10 a involves rotating and pressing the second wafer W2 on the first polishing surface 10 a by the first polishing head 20 a, rotating the first polishing surface 10 a and supplying the first slurry to the first polishing surface 10 a.

The first wafer W1 is also polished on the second polishing surface 10 b by the second polishing head 20 b. This polishing process of the first wafer W1 on the second polishing surface 10 b involves rotating and pressing the first wafer W1 on the second polishing surface 10 b by the second polishing head 20 b, rotating the second polishing surface 10 b and supplying a second slurry to the second polishing surface 10 b.

After the polishing processes are completed, the second wafer W2 and the first wafer W1 are transferred to the second and third wafer load-unload stations 15 b and 15 c, respectively, by rotationally moving the first and second polishing heads 20 a and 20 b to the second and third wafer load-unload stations 15 b and 15 c, respectively. After this rotational movement, the first and second polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 b and 15 c, respectively.

The second wafer W2 is then unloaded from the first polishing head 20 a onto the second wafer load-unload station 15 b. The first wafer W1 is also unloaded from the second polishing head 20 b onto the third wafer load-unload station 15 c. After the first and second wafers W1 and W2 are unloaded, the first and second polishing heads 20 a and 20 b are rotationally moved back to the first and second wafer load-unload stations 15 a and 15 b, respectively. After this movement, the polishing heads 20 a and 20 b are positioned over the wafer load-unload stations 15 a and 15 b, respectively, as illustrated in FIG. 20.

The third wafer W3 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a. The second wafer W2 is also loaded onto the second polishing head 20 b from the second wafer load-unload station 15 b. The first wafer W1 is removed from the third wafer load-unload station 15 c by the wafer transfer device 50. The second and third wafers W2 and W3 are then processed further in the polishing apparatus 1G in the same sequential manner as the first wafer W1.

In this sequential manner, multiple wafers can be continuously processed through the polishing surfaces 10 a and 10 b of the polishing apparatus 1G using the polishing head 20 a and 20 b.

Turning now to FIG. 21, a polishing apparatus 1H according to another embodiment of the invention is shown. The polishing apparatus 1G includes some of the elements of the polishing apparatus 1A of FIGS. 1-3. Thus, same reference numbers used in FIGS. 1-3 will be used to indicate similar elements in FIG. 21. As shown in FIG. 21, the polishing apparatus 1H includes three polishing surfaces 10 a-10 c, three polishing heads 20 a-20 c and four wafer load-unload stations 15 a-15 d. Thus, the polishing apparatus 1H includes the additional wafer load-unload station 15 d. The wafer load-unload stations 15 a-15 d are positioned around the rotational axis 36 such that the wafer load-unload stations are equally spaced to each other around the rotational axis. The polishing surface 10 a is positioned between the first and second wafer load-unload stations 15 a and 15 b. Similarly, the polishing surface 10 b is positioned between the second and third wafer load-unload stations 15 b and 15 c, and the polishing surface 10 c is positioned between the third and fourth wafer load-unload stations 15 c and 15 d.

In this embodiment, the polishing heads 20 a-20 c, which are part of a rotation assembly 12H, are attached to the rotational shaft 30 such that the polishing heads are not equally spaced to each other around the rotational axis 36. Rather, the polishing heads 20 a-20 c are attached to the rotational shaft 30 such that the polishing heads 20 a-20 c can be positioned over the polishing surfaces 10 a-10 c, respectively, or positioned over three of the wafer load-unload stations 15 a-15 d.

In this embodiment, the supporting arms 45 a-45 c, the wafer load-unload stations 15 a-15 d and the polishing surfaces 10 a-10 c are arranged such that (1) the first polishing head 20 a can be moved exclusively between the first wafer load-unload station 15 a, the first polishing surface 20 a and the second wafer load-unload station 15 b; (2) the second polishing head 20 b can be moved exclusively between the second wafer load-unload station 15 b, the second polishing surface 20 b and the third wafer load-unload station 15 b; and (3) the third polishing head 20 c can be moved exclusively between the third wafer load-unload station 15 c, the third polishing surface 20 c and the fourth wafer load-unload station 15 d.

With reference to FIG. 21, a method of processing wafers in the polishing apparatus 1H in accordance with an embodiment is described. Initially, the polishing heads 20 a-20 c are positioned over the first, second and third wafer load-unload stations 15 a-15 c, respectively, as shown in FIG. 21. A first wafer W1 to be processed is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The first wafer W1 is then loaded onto the first polishing head 20 a from the first wafer load-unload station 15 a and is transferred from the first wafer load-unload station 15 a to the first polishing surface 10 a by rotationally moving the first polishing head 20 a from the first wafer load-unload station 15 a to the first polishing surface 10 a. After this movement, the polishing heads 20 a-20 c are positioned over the polishing surfaces 10 a-10 c, respectively. After the first wafer W1 is removed from the first wafer load-unload station 15 a, a second wafer W2 is transferred to and unloaded onto the first wafer load-unload station 15 a by the wafer transfer device 50. The wafers W1 and W2, and subsequent wafers are further processed in the polishing apparatus 1H in the same manner as in the polishing apparatus 1A, up to and including the polishing of the wafers on the polishing surface 10 c.

However, after the polishing process on the polishing surface 10 c is completed, the polished first wafer W1 is transferred to the fourth wafer load-unload station 15 d by rotationally moving the third polishing head 20 c. The first wafer W1 is then unloaded onto the fourth wafer load-unload station 15 d from the third polishing head 20 c, and then removed from the fourth wafer load-unload station 15 d by the wafer transfer device 50. Subsequent wafers are sequentially processed in the same manner.

In this sequential manner, wafers are processed continuously through the polishing surfaces 10 a-10 c using the polishing heads 20 a-20 c. This sequential manner is similar to the sequential manner of processing wafers in the polishing apparatus 1A except that the wafers polished in the polishing apparatus 1H are removed from the third polishing head 20 c to the fourth wafer load-unload station 15 d before being transferred by the wafer transfer device 50.

With reference to a process flow diagram of FIG. 22, a method for polishing semiconductor wafers using a polishing apparatus, such as the polishing apparatus 1A, 1B, 1C, 1D or 1E, in accordance with an embodiment of the invention is described. At block 2202, a semiconductor wafer is transferred between a first wafer station of the polishing apparatus and one of first, second and third polishing heads of a rotation assembly of the polishing apparatus. The first wafer station is a wafer load-unload station. At block 2204, the semiconductor wafer is sequentially polished on first, second and third polishing surfaces of the polishing apparatus using at least one of the first, second and third polishing heads of the rotation assembly. At block 2206, the semiconductor wafer is sequentially transferred to second and third wafer stations of the polishing apparatus using at least one of the first, second and third polishing heads of the rotation assembly. Each of the first, second and third wafer stations is positioned between adjacent polishing surfaces of the first, second and third polishing surfaces.

With reference to a process flow diagram of FIG. 23, a method for polishing semiconductor wafers using a polishing apparatus, such as the polishing apparatus 1F, in accordance with another embodiment of the invention is described. At block 2302, a semiconductor wafer is transferred between a first wafer load-unload station of the polishing apparatus and one of first and second polishing heads of a rotation assembly of the polishing apparatus. At block 2304, the semiconductor wafer is sequentially polished on first and second polishing surfaces of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly. At block 2306, the semiconductor wafer is transferred to a second wafer load-unload station of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly after the semiconductor wafer is polished on the first polishing surface, including unloading the semiconductor wafer onto the second wafer load-unload station. Each of the first and second wafer stations is positioned between the first and second polishing surfaces.

With reference to a process flow diagram of FIG. 24, a method for polishing semiconductor wafers using a polishing apparatus, such as the polishing apparatus 1F, in accordance with another embodiment of the invention is described. At block 2402, a semiconductor wafer is transferred between a first wafer station of the polishing apparatus and one of first and second polishing heads of a rotation assembly of the polishing apparatus. The first wafer station is a wafer load-unload station. At block 2404, the semiconductor wafer is sequentially polished on first and second polishing surfaces of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly. The first and second polishing surfaces are positioned around a rotational axis such that centers of the first and second polishing surfaces and the rotational axis define a first straight line. At block 2406, the semiconductor wafer is transferred to a second wafer station of the polishing apparatus using at least one of the first and second polishing heads of the rotation assembly after the semiconductor wafer is polished on the first polishing surface. The first and second wafer stations are positioned around the rotational axis between the first and second polishing surfaces such that each of the first and second wafer stations is positioned between the first and second polishing surfaces and centers of the first and second wafer stations and the rotational axis define a second straight line. The first and second wafer stations are arranged with respect to the first and second polishing surfaces such that the first straight line is not perpendicular to the second straight line.

With reference to a process flow diagram of FIG. 25, a method for polishing semiconductor wafers using a polishing apparatus, such as the polishing apparatus 1H, in accordance with another embodiment of the invention is described. At block 2502, a semiconductor wafer is transferred to a first wafer station of the polishing apparatus using a wafer transfer device. The first wafer station is a wafer load-unload station. At block 2504, the semiconductor wafer is sequentially transferred to first, second and third polishing surfaces of the polishing apparatus using first, second and third polishing heads, respectively, of a rotation assembly of the polishing apparatus. At block 2506, the semiconductor wafer is sequentially polished on the first, second and third polishing surfaces of the polishing apparatus using the first, second and third polishing heads, respectively, of the rotation assembly. At block 2508, the semiconductor wafer is sequentially transferred to second, third and fourth wafer stations of the polishing apparatus using the first, second and third polishing heads, respectively, of the rotation assembly. The first wafer station is positioned between the fourth wafer station and the first polishing surface. The second wafer station is positioned between the first and second polishing surfaces. The third wafer station is positioned between the second and third polishing surfaces. The fourth wafer station is positioned between the third polishing surface and the first wafer station. At block 2510, the semiconductor wafer is removed from the fourth wafer station of the polishing apparatus using the wafer transfer device. The fourth wafer station is another wafer load-unload station.

With reference to a process flow diagram of FIG. 26, a method for polishing semiconductor wafers using a polishing apparatus, such as the polishing apparatus 1G, in accordance with another embodiment of the invention is described. At block 2602, a semiconductor wafer is transferred to a first wafer station of the polishing apparatus using a wafer transfer device. The first wafer station is a wafer load-unload station. At block 2604, the semiconductor wafer is sequentially transferred to first and second polishing surfaces of the polishing apparatus using first and second polishing heads, respectively, of a rotation assembly of the polishing apparatus. At block 2606, the semiconductor wafer is sequentially polished on the first and second polishing surfaces of the polishing apparatus using the first and second polishing heads, respectively, of the rotation assembly. At block 2608, the semiconductor wafer is sequentially transferred to second and third wafer stations of the polishing apparatus using the first and second polishing heads, respectively, of the rotation assembly. The first wafer station is positioned between the third wafer station and the first polishing surface. The second wafer station is positioned between the first and second polishing surfaces. The third wafer station is positioned between second polishing surface and the first wafer station. At block 2610, the semiconductor wafer is removed from the third wafer station of the polishing apparatus using the wafer transfer device. The third wafer station is another wafer load-unload station.

Although the foregoing description sets forth exemplary embodiments and methods of operation of the invention, the scope of the invention is not limited to these specific embodiments or described methods of operation. Many details have been disclosed that are not necessary to practice the invention, but have been included to sufficiently disclose the best mode of operation and manner and process of making and using the invention. Modification may be made to the specific form and design of the invention without departing from its spirit and scope as expressed in the following claims. 

1. An apparatus for polishing semiconductor wafers, said apparatus comprising: first, second and third polishing surfaces positioned around a rotational axis; first, second and third wafer stations positioned around said rotational axis between said first, second and third polishing surfaces such that each of said first, second and third wafer stations is positioned between adjacent polishing surfaces of said first, second and third polishing surfaces, said first wafer station being a wafer load-unload station configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first wafer station before being transferred from said first wafer station; and a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second and third wafer stations, wherein the number of polishing heads, the number of polishing surfaces and the number of wafer stations included in said apparatus are the same.
 2. The apparatus of claim 1 wherein said first, second and third wafer stations are positioned around said rotational axis such that said first, second and third wafer stations are equally spaced to each other around said rotational axis.
 3. The apparatus of claim 1 wherein said first, second and third polishing surfaces are positioned around said rotational axis such that said first, second and third polishing surfaces are equally spaced to each other around said rotational axis.
 4. The apparatus of claim 1 wherein said second and third wafer stations are wafer load-unload stations configured to load and unload said semiconductor wafers to and from at least one of said first, second and third polishing heads.
 5. The apparatus of claim 4 wherein said rotation assembly is configured to rotate said first, second and third polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer station, said first polishing surface and said second wafer station, said second polishing head is rotated exclusively among said second wafer station, said second polishing surface and said third wafer station, and said third polishing head is rotated exclusively among said third wafer station, said third polishing surface and said first wafer station.
 6. The apparatus of claim 1 wherein each of said second and third wafer stations is a wafer washing station configured to spray fluid onto a particular polishing head of said first, second and third polishing heads to wash said particular polishing head and one of said semiconductor wafers being held by said particular polishing head.
 7. The apparatus of claim 1 wherein said first, second and third polishing heads are coupled to a rotational shaft such that said first, second and third polishing heads are rotationally moved in unison when said rotational shaft is rotated.
 8. The apparatus of claim 7 wherein each of said first, second and third polishing heads is connected to a respective pivoting mechanism that is connected to said rotational shaft so that each of said first, second and third polishing heads can be pivoted about a respective pivoting axis that is rotated by said rotational shaft about said rotational axis.
 9. The apparatus of claim 7 wherein said rotation assembly further includes first, second and third washing arms with spray nozzles to spray fluid onto said first, second and third polishing surfaces when said washing arms are rotated over said first, second and third polishing surfaces.
 10. The apparatus of claim 9 wherein said first, second and third washing arms are attached to said rotational shaft such that said first, second and third washing arms are rotated in unison with said first, second and third polishing heads when said rotational shaft is rotated.
 11. The apparatus of claim 1 further comprising a pivoting wafer transfer device with a wafer load-unload cup, said pivoting wafer transfer device being positioned near said first wafer station such that said wafer load-unload cup can be pivoted to be positioned over said first wafer station to transfer said semiconductor wafers between at least one of said first, second and third polishing heads and said wafer load-unload cup.
 12. An apparatus for polishing semiconductor wafers, said apparatus comprising: first, second and third polishing surfaces positioned around a rotational axis; and first, second, third and fourth wafer load-unload stations positioned around said rotational axis between said first, second and third polishing surfaces such that said second wafer load-unload station is positioned between said first and second polishing surfaces, said third wafer load-unload station is positioned between said second and third polishing surfaces, and said first and fourth wafer load-unload stations are positioned between said first and third polishing surfaces; and a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second, third and fourth wafer load-unload stations.
 13. The apparatus of claim 12 wherein said rotation assembly is configured to rotate said first, second and third polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer load-unload station, said first polishing surface and said second wafer load-unload station, said second polishing head is rotated exclusively among said second wafer load-unload station, said second polishing surface and said third wafer load-unload station, and said third polishing head is rotated exclusively among said third wafer load-unload station, said third polishing surface and said fourth wafer load-unload station.
 14. An apparatus for polishing semiconductor wafers, said apparatus comprising: first and second polishing surfaces positioned around a rotational axis; first and second wafer load-unload stations positioned around said rotational axis between said first and second polishing surfaces such that each of said first and second wafer stations is positioned between said first and second polishing surfaces, each of said first and second wafer load-unload stations being configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first and second wafer load-unload stations before being transferred from said first and second load-unload stations; and a rotation assembly including first and second polishing heads, said rotation assembly being configured to rotationally move each of said first and second polishing heads about said rotational axis between at least some of said first and second polishing surfaces and said first and second wafer load-unload stations, wherein the number of polishing heads, the number of polishing surfaces and the number of wafer load-unload stations included in said apparatus are the same.
 15. The apparatus of claim 14 wherein said first and second polishing surfaces are positioned around said rotational axis such that centers of said first and second polishing surfaces and rotational axis define a first straight line.
 16. The apparatus of claim 15 wherein said first and second wafer load-unload stations are positioned around said rotational axis such that centers of said first and second wafer load-unload stations and said rotational axis define a second straight line.
 17. The apparatus of claim 16 wherein said first and second polishing surfaces and said first and second load-unload wafer stations are arranged such that said first straight line is not perpendicular to said second straight line.
 18. The apparatus of claim 14 wherein said rotation assembly is configured to rotate said first and second polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer load-unload station, said first polishing surface and said second wafer load-unload station, and said second polishing head is rotated exclusively among said second wafer load-unload station, said second polishing surface and said first wafer load-unload station.
 19. The apparatus of claim 14 wherein said first and second polishing heads are coupled to a rotational shaft such that said first and second polishing heads are rotationally moved in unison when said rotational shaft is rotated.
 20. The apparatus of claim 19 wherein each of said first and second polishing heads is connected to a respective pivoting mechanism that is connected to said rotational shaft so that each of said first and second polishing heads can be pivoted about a respective pivoting axis that is rotated by said rotational shaft about said rotational axis.
 21. The apparatus of claim 19 wherein said rotation assembly further includes first and second washing arms with spray nozzles to spray fluid onto said first and second polishing surfaces when said washing arms are rotated over said first and second polishing surfaces.
 22. The apparatus of claim 21 wherein said first and second washing arms are attached to said rotational shaft such that said first and second washing arms are rotated in unison with said first and second polishing heads when said rotational shaft is rotated.
 23. The apparatus of claim 14 further comprising a pivoting wafer transfer device with a wafer load-unload cup, said pivoting wafer transfer device being positioned near said first wafer load-unload station such that said wafer load-unload cup can be pivoted to be positioned over said first wafer load-unload station to transfer said semiconductor wafers between at least one of said first and second polishing heads and said wafer load-unload cup.
 24. An apparatus for polishing semiconductor wafers, said apparatus comprising: first and second polishing surfaces positioned around a rotational axis such that centers of said first and second polishing surfaces and said rotational axis define a first straight line; first and second wafer stations positioned around said rotational axis between said first and second polishing surfaces such that each of said first and second wafer stations is positioned between said first and second polishing surfaces and centers of said first and second wafer stations and said rotational axis define a second straight line, said first and second wafer stations being arranged with respect to said first and second polishing surfaces such that said first straight line is not perpendicular to said second straight line; and a rotation assembly including first and second polishing heads, said rotation assembly being configured to rotationally move each of said first and second polishing heads about said rotational axis between at least some of said first and second polishing surfaces and said first and second wafer stations, wherein the number of polishing heads, the number of polishing surfaces and the number of wafer stations included in said apparatus are the same.
 25. The apparatus of claim 24 wherein said second wafer station is a wafer load-unload station configured to load and unload said semiconductor wafers to and from at least one of said first and second polishing heads.
 26. The apparatus of claim 24 wherein said rotation assembly is configured to rotate said first and second polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer station, said first polishing surface and said second wafer station, and said second polishing head is rotated exclusively among said second wafer station, said second polishing surface and said first wafer station.
 27. The apparatus of claim 24 wherein said second wafer station is a wafer washing station configured to spray fluid onto a particular polishing head of said first and second polishing heads to wash said particular polishing head and one of said semiconductor wafers being held by said particular polishing head.
 28. The apparatus of claim 24 wherein said first and second polishing heads are coupled to a rotational shaft such that said first and second polishing heads are rotationally moved in unison when said rotational shaft is rotated.
 29. The apparatus of claim 28 wherein each of said first and second polishing heads is connected to a respective pivoting mechanism that is connected to said rotational shaft so that each of said first and second polishing heads can be pivoted about a respective pivoting axis that is rotated by said rotational shaft about said rotational axis.
 30. The apparatus of claim 28 wherein said rotation assembly further includes first and second washing arms with spray nozzles to spray fluid onto said first and second polishing surfaces when said washing arms are rotated over said first and second polishing surfaces.
 31. The apparatus of claim 30 wherein said first and second washing arms are attached to said rotational shaft such that said first and second washing arms are rotated in unison with said first and second polishing heads when said rotational shaft is rotated.
 32. The apparatus of claim 24 further comprising a pivoting wafer transfer device with a wafer load-unload cup, said pivoting wafer transfer device being positioned near said first wafer station such that said wafer load-unload cup can be pivoted to be positioned over said first wafer station to transfer said semiconductor wafers between at least one of said first and second polishing heads and said wafer load-unload cup.
 33. An apparatus for polishing semiconductor wafers, said apparatus comprising: first and second polishing surfaces positioned around a rotational axis; first, second and third wafer load-unload stations positioned around said rotational axis between said first and second polishing surfaces such that said first and third load-unload stations are positioned between said first and second polishing surfaces and said second load-unload station is positioned between said first and second polishing surfaces; and a rotation assembly including first and second polishing heads, said rotation assembly being configured to rotationally move each of said first and second polishing heads about said rotational axis between at least some of said first and second polishing surfaces and said first, second and third wafer load-unload stations.
 34. The apparatus of claim 33 wherein said rotation assembly is configured to rotate said first and second polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer load-unload station, said first polishing surface and said second wafer load-unload station, and said second polishing head is rotated exclusively among said second wafer load-unload station, said second polishing surface and said third wafer load-unload station.
 35. A system for polishing semiconductor wafers, said system comprising: first and second polishing apparatuses, each of said first and second polishing apparatuses comprising: first, second and third polishing surfaces positioned around said rotational axis; and first, second and third wafer stations positioned around said rotational axis between said first, second and third polishing surfaces such that each of said first, second and third wafer stations is positioned between adjacent polishing surfaces of said first, second and third polishing surfaces, said first wafer station being a wafer load-unload station configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first wafer station before being transferred from said first wafer station; and a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second and third wafer stations; a wafer transfer device positioned adjacent to said first and second polishing apparatuses to access said first wafer station of each of said first and second polishing apparatuses; and a post-CMP cleaner positioned adjacent to said wafer transfer device such that said wafer transfer device is positioned between said post-CMP cleaner and said first and second polishing apparatuses, said post-CMP cleaner being configured to clean said semiconductor wafers that have been polished in one of said first and second polishing apparatuses and transferred to said post-CMP cleaner by said wafer transfer device.
 36. A system for polishing semiconductor wafers, said system comprising: first and second polishing apparatuses, each of said first and second polishing apparatuses comprising: first, second and third polishing surfaces positioned around said rotational axis; first, second and third wafer stations positioned around said rotational axis between said first, second and third polishing surfaces such that each of said first, second and third wafer stations is positioned between adjacent polishing surfaces of said first, second and third polishing surfaces, said first wafer station being a wafer load-unload station configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first wafer station before being transferred from said first wafer station; a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second and third wafer stations; and a wafer transfer device positioned adjacent to said first and second polishing apparatuses to access said first wafer station of each of said first and second polishing apparatuses, wherein said first and second polishing apparatuses are orientated such that said first wafer station and said first and third polishing surfaces of each of said first and second polishing apparatuses are closer to said wafer transfer device than said second wafer and third wafer stations and said second polishing surface.
 37. The system of claim 36 wherein said first and third polishing surfaces of said first and second polishing apparatuses are linearly arranged.
 38. A method for polishing semiconductor wafers, said method comprising: transferring a semiconductor wafer between a first wafer station of a polishing apparatus and one of first, second and third polishing heads of a rotation assembly of said polishing apparatus, said first wafer station being a wafer load-unload station; sequentially polishing said semiconductor wafer on first, second and third polishing surfaces of said polishing apparatus using at least one of said first, second and third polishing heads of said rotation assembly; and sequentially transferring said semiconductor wafer to second and third wafer stations of said polishing apparatus using at least one of said first, second and third polishing heads of said rotation assembly, each of said first, second and third wafer stations being positioned between adjacent polishing surfaces of said first, second and third polishing surfaces.
 39. The method of claim 38 further comprising: unloading said semiconductor wafer onto said second wafer station from a particular polishing head of said first, second and third polishing heads when said particular polishing head is positioned over said second wafer station; and loading said semiconductor wafer onto a different polishing head of said first, second and third polishing heads from said second wafer station when said different polishing head is positioned over said second wafer station.
 40. The method of claim 38 further comprising spraying fluid from said second wafer station onto said semiconductor wafer when said semiconductor wafer is positioned at said second wafer station.
 41. The method of claim 38 wherein said sequentially transferring includes rotationally moving said first, second and third polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first, second and third polishing heads are coupled.
 42. The method of claim 41 further comprising independently pivoting said first, second and third polishing heads about pivoting axes, each of said pivoting axes being located between one of said first, second and third polishing heads and said rotational axis.
 43. The method of claim 38 further comprising spraying fluid onto said first, second and third polishing surfaces from first, second and third washing arms of said rotation assembly when said washing arms are rotated over said first, second and third polishing surfaces.
 44. The method of claim 38 further comprising: receiving said semiconductor wafer at a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus; pivoting said wafer load-unload cup over said first wafer station; and loading said semiconductor wafer onto one of said first, second and third polishing heads from said wafer load-unload cup.
 45. The method of claim 38 further comprising: unloading said semiconductor wafer onto a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus from one of said first, second and third polishing heads, said wafer load-unload cup being positioned over said first wafer station; and pivoting said wafer load-unload cup away from said first wafer station for removal.
 46. The method of claim 38 further comprising transferring said semiconductor wafer to a fourth wafer station of said polishing apparatus using said third polishing head of said rotation assembly after said semiconductor wafer is polished on said third polishing surface, including unloading said semiconductor wafer onto said fourth wafer station of said polishing apparatus from said third polishing head for removal, said fourth wafer station being positioned between said first wafer station and said third polishing surface.
 47. A method for polishing semiconductor wafers, said method comprising: transferring a semiconductor wafer between a first wafer load-unload station of a polishing apparatus and one of first and second polishing heads of a rotation assembly of said polishing apparatus; sequentially polishing said semiconductor wafer on first and second polishing surfaces of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly; and transferring said semiconductor wafer to a second wafer load-unload station of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly after said semiconductor wafer is polished on said first polishing surface, including unloading said semiconductor wafer onto said second wafer load-unload station, each of said first and second wafer load-unload stations being positioned between said first and second polishing surfaces.
 48. The method of claim 47 wherein said transferring said semiconductor wafer to said second wafer load-unload station includes rotationally moving said first and second polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first and second polishing heads are coupled.
 49. The method of claim 48 further comprising independently pivoting said first, and second polishing heads about pivoting axes, each of said pivoting axes being located between one of said first and second polishing heads and said rotational axis.
 50. The method of claim 47 further comprising spraying fluid onto said first and second polishing surfaces from first and second washing arms of said rotation assembly when said washing arms are rotated over said first and second polishing surfaces.
 51. The method of claim 47 further comprising: receiving said semiconductor wafer at a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus; pivoting said wafer load-unload cup over said first wafer load-unload station; and loading said semiconductor wafer onto one of said first and second polishing heads from said wafer load-unload cup.
 52. The method of claim 47 further comprising: unloading said semiconductor wafer onto a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus from one of said first and second polishing heads, said wafer load-unload cup being positioned over said first wafer load-unload station; and pivoting said wafer load-unload cup away from said first wafer load-unload station for removal.
 53. The method of claim 47 further comprising transferring said semiconductor wafer to a third wafer load-unload station of said polishing apparatus using said second polishing head of said rotation assembly after said semiconductor wafer is polished on said second polishing surface, including unloading said semiconductor wafer onto said third wafer unload-load station from said second polishing head for removal, said third wafer load-unload station being positioned between said first wafer load-unload station and said second polishing surface.
 54. A method for polishing semiconductor wafers, said method comprising: transferring a semiconductor wafer between a first wafer station of a polishing apparatus and one of first and second polishing heads of a rotation assembly of said polishing apparatus, said first wafer station being a wafer load-unload station; sequentially polishing said semiconductor wafer on first and second polishing surfaces of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly, said first and second polishing surfaces being positioned around a rotational axis such that centers of said first and second polishing surfaces and said rotational axis define a first straight line; and transferring said semiconductor wafer to a second wafer station of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly after said semiconductor wafer is polished on said first polishing surface, said first and second wafer stations being positioned around said rotational axis between said first and second polishing surfaces such that each of said first and second wafer stations is positioned between said first and second polishing surfaces and centers of said first and second wafer stations and said rotational axis define a second straight line, said first and second wafer stations being arranged with respect to said first and second polishing surfaces such that said first straight line is not perpendicular to said second straight line.
 55. The method of claim 54 further comprising: unloading said semiconductor wafer onto said second wafer station from said first polishing head; and loading said semiconductor wafer onto said second polishing head from said second wafer station.
 56. The method of claim 54 further comprising spraying fluid from said second wafer station onto said semiconductor wafer when said semiconductor wafer is positioned at said second wafer station.
 57. The method of claim 54 wherein said transferring said semiconductor wafer to said second wafer station includes rotationally moving said first and second polishing heads in unison about said rotational axis by rotating a rotational shaft to which said first and second polishing heads are coupled.
 58. The method of claim 57 further comprising independently pivoting said first, and second polishing heads about pivoting axes, each of said pivoting axes being located between one of said first and second polishing heads and said rotational axis.
 59. The method of claim 54 further comprising spraying fluid onto said first and second polishing surfaces from first and second washing arms of said rotation assembly when said washing arms are rotated over said first and second polishing surfaces.
 60. The method of claim 54 further comprising: receiving said semiconductor wafer at a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus; pivoting said wafer load-unload cup over said first wafer station; and loading said semiconductor wafer onto one of said first and second polishing heads from said wafer load-unload cup.
 61. The method of claim 54 further comprising: unloading said semiconductor wafer onto a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus from one of said first and second polishing heads, said wafer load-unload cup being positioned over said first wafer station; and pivoting said wafer load-unload cup away from said first wafer station for removal.
 62. A method for polishing semiconductor wafers, said method comprising: transferring a semiconductor wafer to a first wafer station of a polishing apparatus using a wafer transfer device, said first wafer station being a wafer load-unload station; sequentially transferring said semiconductor wafer to first, second and third polishing surfaces of said polishing apparatus using first, second and third polishing heads, respectively, of a rotation assembly of said polishing apparatus; sequentially polishing said semiconductor wafer on said first, second and third polishing surfaces of said polishing apparatus using said first, second and third polishing heads, respectively, of said rotation assembly; sequentially transferring said semiconductor wafer to second, third and fourth wafer stations of said polishing apparatus using said first, second and third polishing heads, respectively, of said rotation assembly, said first wafer station being positioned between said fourth wafer station and said first polishing surface, said second wafer station being positioned between said first and second polishing surfaces, said third wafer station being positioned between said second and third polishing surfaces, and said fourth wafer station being positioned between said third polishing surface and said first wafer station; and removing said semiconductor wafer from said fourth wafer station of said polishing apparatus using said wafer transfer device, said fourth wafer station being another wafer load-unload station.
 63. The method of claim 62 wherein said sequentially transferring said semiconductor wafer to said first, second and third polishing surfaces of said polishing apparatus includes rotationally moving said first, second and third polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first, second and third polishing heads are coupled.
 64. A method for polishing semiconductor wafers, said method comprising: transferring a semiconductor wafer to a first wafer station of a polishing apparatus using a wafer transfer device, said first wafer station being a wafer load-unload station; sequentially transferring said semiconductor wafer to first and second polishing surfaces of said polishing apparatus using first and second polishing heads, respectively, of a rotation assembly of said polishing apparatus; sequentially polishing said semiconductor wafer on said first and second polishing surfaces of said polishing apparatus using said first and second polishing heads, respectively, of said rotation assembly; sequentially transferring said semiconductor wafer to second and third wafer stations of said polishing apparatus using said first and second polishing heads, respectively, of said rotation assembly, said first wafer station being positioned between said third wafer station and said first polishing surface, said second wafer station being positioned between said first and second polishing surfaces, said third wafer station being positioned between said second polishing surface and said first wafer station; and removing said semiconductor wafer from said third wafer station of said polishing apparatus using said wafer transfer device, said third wafer station being another wafer load-unload station.
 65. The method of claim 64 wherein said sequentially transferring said semiconductor wafer to said first and second polishing surfaces of said polishing apparatus includes rotationally moving said first and second polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first and second polishing heads are coupled. 